s390/hmcdrv: HMC drive CD/DVD access

This device driver allows accessing a HMC drive CD/DVD-ROM.
It can be used in a LPAR and z/VM environment.

Reviewed-by: Martin Schwidefsky <[e-mail]>
Reviewed-by: Heiko Carstens <[e-mail]>
Signed-off-by: Ralf Hoppe <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/include/asm/irq.h

···
 	IRQEXT_CMS,
 	IRQEXT_CMC,
 	IRQEXT_CMR,
+	IRQEXT_FTP,
 	IRQIO_CIO,
 	IRQIO_QAI,
 	IRQIO_DAS,

arch/s390/kernel/irq.c

···
 	{.irq = IRQEXT_CMS, .name = "CMS", .desc = "[EXT] CPU-Measurement: Sampling"},
 	{.irq = IRQEXT_CMC, .name = "CMC", .desc = "[EXT] CPU-Measurement: Counter"},
 	{.irq = IRQEXT_CMR, .name = "CMR", .desc = "[EXT] CPU-Measurement: RI"},
+	{.irq = IRQEXT_FTP, .name = "FTP", .desc = "[EXT] HMC FTP Service"},
 	{.irq = IRQIO_CIO,  .name = "CIO", .desc = "[I/O] Common I/O Layer Interrupt"},
 	{.irq = IRQIO_QAI,  .name = "QAI", .desc = "[I/O] QDIO Adapter Interrupt"},
 	{.irq = IRQIO_DAS,  .name = "DAS", .desc = "[I/O] DASD"},

drivers/s390/char/Kconfig

···
 	  want for inform other people about your kernel panics,
 	  need this feature and intend to run your kernel in LPAR.
 
+config HMC_DRV
+	def_tristate m
+	prompt "Support for file transfers from HMC drive CD/DVD-ROM"
+	depends on 64BIT
+	select CRC16
+	help
+	  This option enables support for file transfers from a Hardware
+	  Management Console (HMC) drive CD/DVD-ROM. It is available as a
+	  module, called 'hmcdrv', and also as kernel built-in. There is one
+	  optional parameter for this module: cachesize=N, which modifies the
+	  transfer cache size from it's default value 0.5MB to N bytes. If N
+	  is zero, then no caching is performed.
+
 config S390_TAPE
 	def_tristate m
 	prompt "S/390 tape device support"

drivers/s390/char/Makefile

···
 
 zcore_mod-objs := sclp_sdias.o zcore.o
 obj-$(CONFIG_CRASH_DUMP) += zcore_mod.o
+
+hmcdrv-objs := hmcdrv_mod.o hmcdrv_dev.o hmcdrv_ftp.o hmcdrv_cache.o diag_ftp.o sclp_ftp.o
+obj-$(CONFIG_HMC_DRV) += hmcdrv.o

drivers/s390/char/diag_ftp.c

···
+/*
+ *    DIAGNOSE X'2C4' instruction based HMC FTP services, useable on z/VM
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ *
+ */
+
+#define KMSG_COMPONENT "hmcdrv"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/irq.h>
+#include <linux/wait.h>
+#include <linux/string.h>
+#include <asm/ctl_reg.h>
+
+#include "hmcdrv_ftp.h"
+#include "diag_ftp.h"
+
+/* DIAGNOSE X'2C4' return codes in Ry */
+#define DIAG_FTP_RET_OK	0 /* HMC FTP started successfully */
+#define DIAG_FTP_RET_EBUSY	4 /* HMC FTP service currently busy */
+#define DIAG_FTP_RET_EIO	8 /* HMC FTP service I/O error */
+/* and an artificial extension */
+#define DIAG_FTP_RET_EPERM	2 /* HMC FTP service privilege error */
+
+/* FTP service status codes (after INTR at guest real location 133) */
+#define DIAG_FTP_STAT_OK	0U /* request completed successfully */
+#define DIAG_FTP_STAT_PGCC	4U /* program check condition */
+#define DIAG_FTP_STAT_PGIOE	8U /* paging I/O error */
+#define DIAG_FTP_STAT_TIMEOUT	12U /* timeout */
+#define DIAG_FTP_STAT_EBASE	16U /* base of error codes from SCLP */
+#define DIAG_FTP_STAT_LDFAIL	(DIAG_FTP_STAT_EBASE + 1U) /* failed */
+#define DIAG_FTP_STAT_LDNPERM	(DIAG_FTP_STAT_EBASE + 2U) /* not allowed */
+#define DIAG_FTP_STAT_LDRUNS	(DIAG_FTP_STAT_EBASE + 3U) /* runs */
+#define DIAG_FTP_STAT_LDNRUNS	(DIAG_FTP_STAT_EBASE + 4U) /* not runs */
+
+/**
+ * struct diag_ftp_ldfpl - load file FTP parameter list (LDFPL)
+ * @bufaddr: real buffer address (at 4k boundary)
+ * @buflen: length of buffer
+ * @offset: dir/file offset
+ * @intparm: interruption parameter (unused)
+ * @transferred: bytes transferred
+ * @fsize: file size, filled on GET
+ * @failaddr: failing address
+ * @spare: padding
+ * @fident: file name - ASCII
+ */
+struct diag_ftp_ldfpl {
+	u64 bufaddr;
+	u64 buflen;
+	u64 offset;
+	u64 intparm;
+	u64 transferred;
+	u64 fsize;
+	u64 failaddr;
+	u64 spare;
+	u8 fident[HMCDRV_FTP_FIDENT_MAX];
+} __packed;
+
+static DECLARE_COMPLETION(diag_ftp_rx_complete);
+static int diag_ftp_subcode;
+
+/**
+ * diag_ftp_handler() - FTP services IRQ handler
+ * @extirq: external interrupt (sub-) code
+ * @param32: 32-bit interruption parameter from &struct diag_ftp_ldfpl
+ * @param64: unused (for 64-bit interrupt parameters)
+ */
+static void diag_ftp_handler(struct ext_code extirq,
+			     unsigned int param32,
+			     unsigned long param64)
+{
+	if ((extirq.subcode >> 8) != 8)
+		return; /* not a FTP services sub-code */
+
+	inc_irq_stat(IRQEXT_FTP);
+	diag_ftp_subcode = extirq.subcode & 0xffU;
+	complete(&diag_ftp_rx_complete);
+}
+
+/**
+ * diag_ftp_2c4() - DIAGNOSE X'2C4' service call
+ * @fpl: pointer to prepared LDFPL
+ * @cmd: FTP command to be executed
+ *
+ * Performs a DIAGNOSE X'2C4' call with (input/output) FTP parameter list
+ * @fpl and FTP function code @cmd. In case of an error the function does
+ * nothing and returns an (negative) error code.
+ *
+ * Notes:
+ * 1. This function only initiates a transfer, so the caller must wait
+ *    for completion (asynchronous execution).
+ * 2. The FTP parameter list @fpl must be aligned to a double-word boundary.
+ * 3. fpl->bufaddr must be a real address, 4k aligned
+ */
+static int diag_ftp_2c4(struct diag_ftp_ldfpl *fpl,
+			enum hmcdrv_ftp_cmdid cmd)
+{
+	int rc;
+
+	asm volatile(
+		"	diag	%[addr],%[cmd],0x2c4\n"
+		"0:	j	2f\n"
+		"1:	la	%[rc],%[err]\n"
+		"2:\n"
+		EX_TABLE(0b, 1b)
+		: [rc] "=d" (rc), "+m" (*fpl)
+		: [cmd] "0" (cmd), [addr] "d" (virt_to_phys(fpl)),
+		  [err] "i" (DIAG_FTP_RET_EPERM)
+		: "cc");
+
+	switch (rc) {
+	case DIAG_FTP_RET_OK:
+		return 0;
+	case DIAG_FTP_RET_EBUSY:
+		return -EBUSY;
+	case DIAG_FTP_RET_EPERM:
+		return -EPERM;
+	case DIAG_FTP_RET_EIO:
+	default:
+		return -EIO;
+	}
+}
+
+/**
+ * diag_ftp_cmd() - executes a DIAG X'2C4' FTP command, targeting a HMC
+ * @ftp: pointer to FTP command specification
+ * @fsize: return of file size (or NULL if undesirable)
+ *
+ * Attention: Notice that this function is not reentrant - so the caller
+ * must ensure locking.
+ *
+ * Return: number of bytes read/written or a (negative) error code
+ */
+ssize_t diag_ftp_cmd(const struct hmcdrv_ftp_cmdspec *ftp, size_t *fsize)
+{
+	struct diag_ftp_ldfpl *ldfpl;
+	ssize_t len;
+#ifdef DEBUG
+	unsigned long start_jiffies;
+
+	pr_debug("starting DIAG X'2C4' on '%s', requesting %zd bytes\n",
+		 ftp->fname, ftp->len);
+	start_jiffies = jiffies;
+#endif
+	init_completion(&diag_ftp_rx_complete);
+
+	ldfpl = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!ldfpl) {
+		len = -ENOMEM;
+		goto out;
+	}
+
+	len = strlcpy(ldfpl->fident, ftp->fname, sizeof(ldfpl->fident));
+	if (len >= HMCDRV_FTP_FIDENT_MAX) {
+		len = -EINVAL;
+		goto out_free;
+	}
+
+	ldfpl->transferred = 0;
+	ldfpl->fsize = 0;
+	ldfpl->offset = ftp->ofs;
+	ldfpl->buflen = ftp->len;
+	ldfpl->bufaddr = virt_to_phys(ftp->buf);
+
+	len = diag_ftp_2c4(ldfpl, ftp->id);
+	if (len)
+		goto out_free;
+
+	/*
+	 * There is no way to cancel the running diag X'2C4', the code
+	 * needs to wait unconditionally until the transfer is complete.
+	 */
+	wait_for_completion(&diag_ftp_rx_complete);
+
+#ifdef DEBUG
+	pr_debug("completed DIAG X'2C4' after %lu ms\n",
+		 (jiffies - start_jiffies) * 1000 / HZ);
+	pr_debug("status of DIAG X'2C4' is %u, with %lld/%lld bytes\n",
+		 diag_ftp_subcode, ldfpl->transferred, ldfpl->fsize);
+#endif
+
+	switch (diag_ftp_subcode) {
+	case DIAG_FTP_STAT_OK: /* success */
+		len = ldfpl->transferred;
+		if (fsize)
+			*fsize = ldfpl->fsize;
+		break;
+	case DIAG_FTP_STAT_LDNPERM:
+		len = -EPERM;
+		break;
+	case DIAG_FTP_STAT_LDRUNS:
+		len = -EBUSY;
+		break;
+	case DIAG_FTP_STAT_LDFAIL:
+		len = -ENOENT; /* no such file or media */
+		break;
+	default:
+		len = -EIO;
+		break;
+	}
+
+out_free:
+	free_page((unsigned long) ldfpl);
+out:
+	return len;
+}
+
+/**
+ * diag_ftp_startup() - startup of FTP services, when running on z/VM
+ *
+ * Return: 0 on success, else an (negative) error code
+ */
+int diag_ftp_startup(void)
+{
+	int rc;
+
+	rc = register_external_irq(EXT_IRQ_CP_SERVICE, diag_ftp_handler);
+	if (rc)
+		return rc;
+
+	ctl_set_bit(0, 63 - 22);
+	return 0;
+}
+
+/**
+ * diag_ftp_shutdown() - shutdown of FTP services, when running on z/VM
+ */
+void diag_ftp_shutdown(void)
+{
+	ctl_clear_bit(0, 63 - 22);
+	unregister_external_irq(EXT_IRQ_CP_SERVICE, diag_ftp_handler);
+}

drivers/s390/char/diag_ftp.h

···
+/*
+ *    DIAGNOSE X'2C4' instruction based SE/HMC FTP Services, useable on z/VM
+ *
+ *    Notice that all functions exported here are not reentrant.
+ *    So usage should be exclusive, ensured by the caller (e.g. using a
+ *    mutex).
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ */
+
+#ifndef __DIAG_FTP_H__
+#define __DIAG_FTP_H__
+
+#include "hmcdrv_ftp.h"
+
+int diag_ftp_startup(void);
+void diag_ftp_shutdown(void);
+ssize_t diag_ftp_cmd(const struct hmcdrv_ftp_cmdspec *ftp, size_t *fsize);
+
+#endif	 /* __DIAG_FTP_H__ */

drivers/s390/char/hmcdrv_cache.c

···
+/*
+ *    SE/HMC Drive (Read) Cache Functions
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ *
+ */
+
+#define KMSG_COMPONENT "hmcdrv"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/jiffies.h>
+
+#include "hmcdrv_ftp.h"
+#include "hmcdrv_cache.h"
+
+#define HMCDRV_CACHE_TIMEOUT		30 /* aging timeout in seconds */
+
+/**
+ * struct hmcdrv_cache_entry - file cache (only used on read/dir)
+ * @id: FTP command ID
+ * @content: kernel-space buffer, 4k aligned
+ * @len: size of @content cache (0 if caching disabled)
+ * @ofs: start of content within file (-1 if no cached content)
+ * @fname: file name
+ * @fsize: file size
+ * @timeout: cache timeout in jiffies
+ *
+ * Notice that the first three members (id, fname, fsize) are cached on all
+ * read/dir requests. But content is cached only under some preconditions.
+ * Uncached content is signalled by a negative value of @ofs.
+ */
+struct hmcdrv_cache_entry {
+	enum hmcdrv_ftp_cmdid id;
+	char fname[HMCDRV_FTP_FIDENT_MAX];
+	size_t fsize;
+	loff_t ofs;
+	unsigned long timeout;
+	void *content;
+	size_t len;
+};
+
+static int hmcdrv_cache_order; /* cache allocated page order */
+
+static struct hmcdrv_cache_entry hmcdrv_cache_file = {
+	.fsize = SIZE_MAX,
+	.ofs = -1,
+	.len = 0,
+	.fname = {'\0'}
+};
+
+/**
+ * hmcdrv_cache_get() - looks for file data/content in read cache
+ * @ftp: pointer to FTP command specification
+ *
+ * Return: number of bytes read from cache or a negative number if nothing
+ * in content cache (for the file/cmd specified in @ftp)
+ */
+static ssize_t hmcdrv_cache_get(const struct hmcdrv_ftp_cmdspec *ftp)
+{
+	loff_t pos; /* position in cache (signed) */
+	ssize_t len;
+
+	if ((ftp->id != hmcdrv_cache_file.id) ||
+	    strcmp(hmcdrv_cache_file.fname, ftp->fname))
+		return -1;
+
+	if (ftp->ofs >= hmcdrv_cache_file.fsize) /* EOF ? */
+		return 0;
+
+	if ((hmcdrv_cache_file.ofs < 0) || /* has content? */
+	    time_after(jiffies, hmcdrv_cache_file.timeout))
+		return -1;
+
+	/* there seems to be cached content - calculate the maximum number
+	 * of bytes that can be returned (regarding file size and offset)
+	 */
+	len = hmcdrv_cache_file.fsize - ftp->ofs;
+
+	if (len > ftp->len)
+		len = ftp->len;
+
+	/* check if the requested chunk falls into our cache (which starts
+	 * at offset 'hmcdrv_cache_file.ofs' in the file of interest)
+	 */
+	pos = ftp->ofs - hmcdrv_cache_file.ofs;
+
+	if ((pos >= 0) &&
+	    ((pos + len) <= hmcdrv_cache_file.len)) {
+
+		memcpy(ftp->buf,
+		       hmcdrv_cache_file.content + pos,
+		       len);
+		pr_debug("using cached content of '%s', returning %zd/%zd bytes\n",
+			 hmcdrv_cache_file.fname, len,
+			 hmcdrv_cache_file.fsize);
+
+		return len;
+	}
+
+	return -1;
+}
+
+/**
+ * hmcdrv_cache_do() - do a HMC drive CD/DVD transfer with cache update
+ * @ftp: pointer to FTP command specification
+ * @func: FTP transfer function to be used
+ *
+ * Return: number of bytes read/written or a (negative) error code
+ */
+static ssize_t hmcdrv_cache_do(const struct hmcdrv_ftp_cmdspec *ftp,
+			       hmcdrv_cache_ftpfunc func)
+{
+	ssize_t len;
+
+	/* only cache content if the read/dir cache really exists
+	 * (hmcdrv_cache_file.len > 0), is large enough to handle the
+	 * request (hmcdrv_cache_file.len >= ftp->len) and there is a need
+	 * to do so (ftp->len > 0)
+	 */
+	if ((ftp->len > 0) && (hmcdrv_cache_file.len >= ftp->len)) {
+
+		/* because the cache is not located at ftp->buf, we have to
+		 * assemble a new HMC drive FTP cmd specification (pointing
+		 * to our cache, and using the increased size)
+		 */
+		struct hmcdrv_ftp_cmdspec cftp = *ftp; /* make a copy */
+		cftp.buf = hmcdrv_cache_file.content;  /* and update */
+		cftp.len = hmcdrv_cache_file.len;      /* buffer data */
+
+		len = func(&cftp, &hmcdrv_cache_file.fsize); /* now do */
+
+		if (len > 0) {
+			pr_debug("caching %zd bytes content for '%s'\n",
+				 len, ftp->fname);
+
+			if (len > ftp->len)
+				len = ftp->len;
+
+			hmcdrv_cache_file.ofs = ftp->ofs;
+			hmcdrv_cache_file.timeout = jiffies +
+				HMCDRV_CACHE_TIMEOUT * HZ;
+			memcpy(ftp->buf, hmcdrv_cache_file.content, len);
+		}
+	} else {
+		len = func(ftp, &hmcdrv_cache_file.fsize);
+		hmcdrv_cache_file.ofs = -1; /* invalidate content */
+	}
+
+	if (len > 0) {
+		/* cache some file info (FTP command, file name and file
+		 * size) unconditionally
+		 */
+		strlcpy(hmcdrv_cache_file.fname, ftp->fname,
+			HMCDRV_FTP_FIDENT_MAX);
+		hmcdrv_cache_file.id = ftp->id;
+		pr_debug("caching cmd %d, file size %zu for '%s'\n",
+			 ftp->id, hmcdrv_cache_file.fsize, ftp->fname);
+	}
+
+	return len;
+}
+
+/**
+ * hmcdrv_cache_cmd() - perform a cached HMC drive CD/DVD transfer
+ * @ftp: pointer to FTP command specification
+ * @func: FTP transfer function to be used
+ *
+ * Attention: Notice that this function is not reentrant - so the caller
+ * must ensure exclusive execution.
+ *
+ * Return: number of bytes read/written or a (negative) error code
+ */
+ssize_t hmcdrv_cache_cmd(const struct hmcdrv_ftp_cmdspec *ftp,
+			 hmcdrv_cache_ftpfunc func)
+{
+	ssize_t len;
+
+	if ((ftp->id == HMCDRV_FTP_DIR) || /* read cache */
+	    (ftp->id == HMCDRV_FTP_NLIST) ||
+	    (ftp->id == HMCDRV_FTP_GET)) {
+
+		len = hmcdrv_cache_get(ftp);
+
+		if (len >= 0) /* got it from cache ? */
+			return len; /* yes */
+
+		len = hmcdrv_cache_do(ftp, func);
+
+		if (len >= 0)
+			return len;
+
+	} else {
+		len = func(ftp, NULL); /* simply do original command */
+	}
+
+	/* invalidate the (read) cache in case there was a write operation
+	 * or an error on read/dir
+	 */
+	hmcdrv_cache_file.id = HMCDRV_FTP_NOOP;
+	hmcdrv_cache_file.fsize = LLONG_MAX;
+	hmcdrv_cache_file.ofs = -1;
+
+	return len;
+}
+
+/**
+ * hmcdrv_cache_startup() - startup of HMC drive cache
+ * @cachesize: cache size
+ *
+ * Return: 0 on success, else a (negative) error code
+ */
+int hmcdrv_cache_startup(size_t cachesize)
+{
+	if (cachesize > 0) { /* perform caching ? */
+		hmcdrv_cache_order = get_order(cachesize);
+		hmcdrv_cache_file.content =
+			(void *) __get_free_pages(GFP_KERNEL | GFP_DMA,
+						  hmcdrv_cache_order);
+
+		if (!hmcdrv_cache_file.content) {
+			pr_err("Allocating the requested cache size of %zu bytes failed\n",
+			       cachesize);
+			return -ENOMEM;
+		}
+
+		pr_debug("content cache enabled, size is %zu bytes\n",
+			 cachesize);
+	}
+
+	hmcdrv_cache_file.len = cachesize;
+	return 0;
+}
+
+/**
+ * hmcdrv_cache_shutdown() - shutdown of HMC drive cache
+ */
+void hmcdrv_cache_shutdown(void)
+{
+	if (hmcdrv_cache_file.content) {
+		free_pages((unsigned long) hmcdrv_cache_file.content,
+			   hmcdrv_cache_order);
+		hmcdrv_cache_file.content = NULL;
+	}
+
+	hmcdrv_cache_file.id = HMCDRV_FTP_NOOP;
+	hmcdrv_cache_file.fsize = LLONG_MAX;
+	hmcdrv_cache_file.ofs = -1;
+	hmcdrv_cache_file.len = 0; /* no cache */
+}

drivers/s390/char/hmcdrv_cache.h

···
+/*
+ *    SE/HMC Drive (Read) Cache Functions
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ */
+
+#ifndef __HMCDRV_CACHE_H__
+#define __HMCDRV_CACHE_H__
+
+#include <linux/mmzone.h>
+#include "hmcdrv_ftp.h"
+
+#define HMCDRV_CACHE_SIZE_DFLT	(MAX_ORDER_NR_PAGES * PAGE_SIZE / 2UL)
+
+typedef ssize_t (*hmcdrv_cache_ftpfunc)(const struct hmcdrv_ftp_cmdspec *ftp,
+					size_t *fsize);
+
+ssize_t hmcdrv_cache_cmd(const struct hmcdrv_ftp_cmdspec *ftp,
+			 hmcdrv_cache_ftpfunc func);
+int hmcdrv_cache_startup(size_t cachesize);
+void hmcdrv_cache_shutdown(void);
+
+#endif	 /* __HMCDRV_CACHE_H__ */

drivers/s390/char/hmcdrv_dev.c

···
+/*
+ *    HMC Drive CD/DVD Device
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ *
+ *    This file provides a Linux "misc" character device for access to an
+ *    assigned HMC drive CD/DVD-ROM. It works as follows: First create the
+ *    device by calling hmcdrv_dev_init(). After open() a lseek(fd, 0,
+ *    SEEK_END) indicates that a new FTP command follows (not needed on the
+ *    first command after open). Then write() the FTP command ASCII string
+ *    to it, e.g. "dir /" or "nls <directory>" or "get <filename>". At the
+ *    end read() the response.
+ */
+
+#define KMSG_COMPONENT "hmcdrv"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/miscdevice.h>
+#include <linux/device.h>
+#include <linux/capability.h>
+#include <linux/delay.h>
+#include <linux/uaccess.h>
+
+#include "hmcdrv_dev.h"
+#include "hmcdrv_ftp.h"
+
+/* If the following macro is defined, then the HMC device creates it's own
+ * separated device class (and dynamically assigns a major number). If not
+ * defined then the HMC device is assigned to the "misc" class devices.
+ *
+#define HMCDRV_DEV_CLASS "hmcftp"
+ */
+
+#define HMCDRV_DEV_NAME  "hmcdrv"
+#define HMCDRV_DEV_BUSY_DELAY	 500 /* delay between -EBUSY trials in ms */
+#define HMCDRV_DEV_BUSY_RETRIES  3   /* number of retries on -EBUSY */
+
+struct hmcdrv_dev_node {
+
+#ifdef HMCDRV_DEV_CLASS
+	struct cdev dev; /* character device structure */
+	umode_t mode;	 /* mode of device node (unused, zero) */
+#else
+	struct miscdevice dev; /* "misc" device structure */
+#endif
+
+};
+
+static int hmcdrv_dev_open(struct inode *inode, struct file *fp);
+static int hmcdrv_dev_release(struct inode *inode, struct file *fp);
+static loff_t hmcdrv_dev_seek(struct file *fp, loff_t pos, int whence);
+static ssize_t hmcdrv_dev_read(struct file *fp, char __user *ubuf,
+			       size_t len, loff_t *pos);
+static ssize_t hmcdrv_dev_write(struct file *fp, const char __user *ubuf,
+				size_t len, loff_t *pos);
+static ssize_t hmcdrv_dev_transfer(char __kernel *cmd, loff_t offset,
+				   char __user *buf, size_t len);
+
+/*
+ * device operations
+ */
+static const struct file_operations hmcdrv_dev_fops = {
+	.open = hmcdrv_dev_open,
+	.llseek = hmcdrv_dev_seek,
+	.release = hmcdrv_dev_release,
+	.read = hmcdrv_dev_read,
+	.write = hmcdrv_dev_write,
+};
+
+static struct hmcdrv_dev_node hmcdrv_dev; /* HMC device struct (static) */
+
+#ifdef HMCDRV_DEV_CLASS
+
+static struct class *hmcdrv_dev_class; /* device class pointer */
+static dev_t hmcdrv_dev_no; /* device number (major/minor) */
+
+/**
+ * hmcdrv_dev_name() - provides a naming hint for a device node in /dev
+ * @dev: device for which the naming/mode hint is
+ * @mode: file mode for device node created in /dev
+ *
+ * See: devtmpfs.c, function devtmpfs_create_node()
+ *
+ * Return: recommended device file name in /dev
+ */
+static char *hmcdrv_dev_name(struct device *dev, umode_t *mode)
+{
+	char *nodename = NULL;
+	const char *devname = dev_name(dev); /* kernel device name */
+
+	if (devname)
+		nodename = kasprintf(GFP_KERNEL, "%s", devname);
+
+	/* on device destroy (rmmod) the mode pointer may be NULL
+	 */
+	if (mode)
+		*mode = hmcdrv_dev.mode;
+
+	return nodename;
+}
+
+#endif	/* HMCDRV_DEV_CLASS */
+
+/*
+ * open()
+ */
+static int hmcdrv_dev_open(struct inode *inode, struct file *fp)
+{
+	int rc;
+
+	/* check for non-blocking access, which is really unsupported
+	 */
+	if (fp->f_flags & O_NONBLOCK)
+		return -EINVAL;
+
+	/* Because it makes no sense to open this device read-only (then a
+	 * FTP command cannot be emitted), we respond with an error.
+	 */
+	if ((fp->f_flags & O_ACCMODE) == O_RDONLY)
+		return -EINVAL;
+
+	/* prevent unloading this module as long as anyone holds the
+	 * device file open - so increment the reference count here
+	 */
+	if (!try_module_get(THIS_MODULE))
+		return -ENODEV;
+
+	fp->private_data = NULL; /* no command yet */
+	rc = hmcdrv_ftp_startup();
+	if (rc)
+		module_put(THIS_MODULE);
+
+	pr_debug("open file '/dev/%s' with return code %d\n",
+		 fp->f_dentry->d_name.name, rc);
+	return rc;
+}
+
+/*
+ * release()
+ */
+static int hmcdrv_dev_release(struct inode *inode, struct file *fp)
+{
+	pr_debug("closing file '/dev/%s'\n", fp->f_dentry->d_name.name);
+	kfree(fp->private_data);
+	fp->private_data = NULL;
+	hmcdrv_ftp_shutdown();
+	module_put(THIS_MODULE);
+	return 0;
+}
+
+/*
+ * lseek()
+ */
+static loff_t hmcdrv_dev_seek(struct file *fp, loff_t pos, int whence)
+{
+	switch (whence) {
+	case SEEK_CUR: /* relative to current file position */
+		pos += fp->f_pos; /* new position stored in 'pos' */
+		break;
+
+	case SEEK_SET: /* absolute (relative to beginning of file) */
+		break; /* SEEK_SET */
+
+		/* We use SEEK_END as a special indicator for a SEEK_SET
+		 * (set absolute position), combined with a FTP command
+		 * clear.
+		 */
+	case SEEK_END:
+		if (fp->private_data) {
+			kfree(fp->private_data);
+			fp->private_data = NULL;
+		}
+
+		break; /* SEEK_END */
+
+	default: /* SEEK_DATA, SEEK_HOLE: unsupported */
+		return -EINVAL;
+	}
+
+	if (pos < 0)
+		return -EINVAL;
+
+	if (fp->f_pos != pos)
+		++fp->f_version;
+
+	fp->f_pos = pos;
+	return pos;
+}
+
+/*
+ * transfer (helper function)
+ */
+static ssize_t hmcdrv_dev_transfer(char __kernel *cmd, loff_t offset,
+				   char __user *buf, size_t len)
+{
+	ssize_t retlen;
+	unsigned trials = HMCDRV_DEV_BUSY_RETRIES;
+
+	do {
+		retlen = hmcdrv_ftp_cmd(cmd, offset, buf, len);
+
+		if (retlen != -EBUSY)
+			break;
+
+		msleep(HMCDRV_DEV_BUSY_DELAY);
+
+	} while (--trials > 0);
+
+	return retlen;
+}
+
+/*
+ * read()
+ */
+static ssize_t hmcdrv_dev_read(struct file *fp, char __user *ubuf,
+			       size_t len, loff_t *pos)
+{
+	ssize_t retlen;
+
+	if (((fp->f_flags & O_ACCMODE) == O_WRONLY) ||
+	    (fp->private_data == NULL)) { /* no FTP cmd defined ? */
+		return -EBADF;
+	}
+
+	retlen = hmcdrv_dev_transfer((char *) fp->private_data,
+				     *pos, ubuf, len);
+
+	pr_debug("read from file '/dev/%s' at %lld returns %zd/%zu\n",
+		 fp->f_dentry->d_name.name, (long long) *pos, retlen, len);
+
+	if (retlen > 0)
+		*pos += retlen;
+
+	return retlen;
+}
+
+/*
+ * write()
+ */
+static ssize_t hmcdrv_dev_write(struct file *fp, const char __user *ubuf,
+				size_t len, loff_t *pos)
+{
+	ssize_t retlen;
+
+	pr_debug("writing file '/dev/%s' at pos. %lld with length %zd\n",
+		 fp->f_dentry->d_name.name, (long long) *pos, len);
+
+	if (!fp->private_data) { /* first expect a cmd write */
+		fp->private_data = kmalloc(len + 1, GFP_KERNEL);
+
+		if (!fp->private_data)
+			return -ENOMEM;
+
+		if (!copy_from_user(fp->private_data, ubuf, len)) {
+			((char *)fp->private_data)[len] = '\0';
+			return len;
+		}
+
+		kfree(fp->private_data);
+		fp->private_data = NULL;
+		return -EFAULT;
+	}
+
+	retlen = hmcdrv_dev_transfer((char *) fp->private_data,
+				     *pos, (char __user *) ubuf, len);
+	if (retlen > 0)
+		*pos += retlen;
+
+	pr_debug("write to file '/dev/%s' returned %zd\n",
+		 fp->f_dentry->d_name.name, retlen);
+
+	return retlen;
+}
+
+/**
+ * hmcdrv_dev_init() - creates a HMC drive CD/DVD device
+ *
+ * This function creates a HMC drive CD/DVD kernel device and an associated
+ * device under /dev, using a dynamically allocated major number.
+ *
+ * Return: 0 on success, else an error code.
+ */
+int hmcdrv_dev_init(void)
+{
+	int rc;
+
+#ifdef HMCDRV_DEV_CLASS
+	struct device *dev;
+
+	rc = alloc_chrdev_region(&hmcdrv_dev_no, 0, 1, HMCDRV_DEV_NAME);
+
+	if (rc)
+		goto out_err;
+
+	cdev_init(&hmcdrv_dev.dev, &hmcdrv_dev_fops);
+	hmcdrv_dev.dev.owner = THIS_MODULE;
+	rc = cdev_add(&hmcdrv_dev.dev, hmcdrv_dev_no, 1);
+
+	if (rc)
+		goto out_unreg;
+
+	/* At this point the character device exists in the kernel (see
+	 * /proc/devices), but not under /dev nor /sys/devices/virtual. So
+	 * we have to create an associated class (see /sys/class).
+	 */
+	hmcdrv_dev_class = class_create(THIS_MODULE, HMCDRV_DEV_CLASS);
+
+	if (IS_ERR(hmcdrv_dev_class)) {
+		rc = PTR_ERR(hmcdrv_dev_class);
+		goto out_devdel;
+	}
+
+	/* Finally a device node in /dev has to be established (as 'mkdev'
+	 * does from the command line). Notice that assignment of a device
+	 * node name/mode function is optional (only for mode != 0600).
+	 */
+	hmcdrv_dev.mode = 0; /* "unset" */
+	hmcdrv_dev_class->devnode = hmcdrv_dev_name;
+
+	dev = device_create(hmcdrv_dev_class, NULL, hmcdrv_dev_no, NULL,
+			    "%s", HMCDRV_DEV_NAME);
+	if (!IS_ERR(dev))
+		return 0;
+
+	rc = PTR_ERR(dev);
+	class_destroy(hmcdrv_dev_class);
+	hmcdrv_dev_class = NULL;
+
+out_devdel:
+	cdev_del(&hmcdrv_dev.dev);
+
+out_unreg:
+	unregister_chrdev_region(hmcdrv_dev_no, 1);
+
+out_err:
+
+#else  /* !HMCDRV_DEV_CLASS */
+	hmcdrv_dev.dev.minor = MISC_DYNAMIC_MINOR;
+	hmcdrv_dev.dev.name = HMCDRV_DEV_NAME;
+	hmcdrv_dev.dev.fops = &hmcdrv_dev_fops;
+	hmcdrv_dev.dev.mode = 0; /* finally produces 0600 */
+	rc = misc_register(&hmcdrv_dev.dev);
+#endif	/* HMCDRV_DEV_CLASS */
+
+	return rc;
+}
+
+/**
+ * hmcdrv_dev_exit() - destroys a HMC drive CD/DVD device
+ */
+void hmcdrv_dev_exit(void)
+{
+#ifdef HMCDRV_DEV_CLASS
+	if (!IS_ERR_OR_NULL(hmcdrv_dev_class)) {
+		device_destroy(hmcdrv_dev_class, hmcdrv_dev_no);
+		class_destroy(hmcdrv_dev_class);
+	}
+
+	cdev_del(&hmcdrv_dev.dev);
+	unregister_chrdev_region(hmcdrv_dev_no, 1);
+#else  /* !HMCDRV_DEV_CLASS */
+	misc_deregister(&hmcdrv_dev.dev);
+#endif	/* HMCDRV_DEV_CLASS */
+}

drivers/s390/char/hmcdrv_dev.h

···
+/*
+ *    SE/HMC Drive FTP Device
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ */
+
+#ifndef __HMCDRV_DEV_H__
+#define __HMCDRV_DEV_H__
+
+int hmcdrv_dev_init(void);
+void hmcdrv_dev_exit(void);
+
+#endif	 /* __HMCDRV_DEV_H__ */

drivers/s390/char/hmcdrv_ftp.c

···
+/*
+ *    HMC Drive FTP Services
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ */
+
+#define KMSG_COMPONENT "hmcdrv"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/export.h>
+
+#include <linux/ctype.h>
+#include <linux/crc16.h>
+
+#include "hmcdrv_ftp.h"
+#include "hmcdrv_cache.h"
+#include "sclp_ftp.h"
+#include "diag_ftp.h"
+
+/**
+ * struct hmcdrv_ftp_ops - HMC drive FTP operations
+ * @startup: startup function
+ * @shutdown: shutdown function
+ * @cmd: FTP transfer function
+ */
+struct hmcdrv_ftp_ops {
+	int (*startup)(void);
+	void (*shutdown)(void);
+	ssize_t (*transfer)(const struct hmcdrv_ftp_cmdspec *ftp,
+			    size_t *fsize);
+};
+
+static enum hmcdrv_ftp_cmdid hmcdrv_ftp_cmd_getid(const char *cmd, int len);
+static int hmcdrv_ftp_parse(char *cmd, struct hmcdrv_ftp_cmdspec *ftp);
+
+static struct hmcdrv_ftp_ops *hmcdrv_ftp_funcs; /* current operations */
+static DEFINE_MUTEX(hmcdrv_ftp_mutex); /* mutex for hmcdrv_ftp_funcs */
+static unsigned hmcdrv_ftp_refcnt; /* start/shutdown reference counter */
+
+/**
+ * hmcdrv_ftp_cmd_getid() - determine FTP command ID from a command string
+ * @cmd: FTP command string (NOT zero-terminated)
+ * @len: length of FTP command string in @cmd
+ */
+static enum hmcdrv_ftp_cmdid hmcdrv_ftp_cmd_getid(const char *cmd, int len)
+{
+	/* HMC FTP command descriptor */
+	struct hmcdrv_ftp_cmd_desc {
+		const char *str;	   /* command string */
+		enum hmcdrv_ftp_cmdid cmd; /* associated command as enum */
+	};
+
+	/* Description of all HMC drive FTP commands
+	 *
+	 * Notes:
+	 * 1. Array size should be a prime number.
+	 * 2. Do not change the order of commands in table (because the
+	 *    index is determined by CRC % ARRAY_SIZE).
+	 * 3. Original command 'nlist' was renamed, else the CRC would
+	 *    collide with 'append' (see point 2).
+	 */
+	static const struct hmcdrv_ftp_cmd_desc ftpcmds[7] = {
+
+		{.str = "get", /* [0] get (CRC = 0x68eb) */
+		 .cmd = HMCDRV_FTP_GET},
+		{.str = "dir", /* [1] dir (CRC = 0x6a9e) */
+		 .cmd = HMCDRV_FTP_DIR},
+		{.str = "delete", /* [2] delete (CRC = 0x53ae) */
+		 .cmd = HMCDRV_FTP_DELETE},
+		{.str = "nls", /* [3] nls (CRC = 0xf87c) */
+		 .cmd = HMCDRV_FTP_NLIST},
+		{.str = "put", /* [4] put (CRC = 0xac56) */
+		 .cmd = HMCDRV_FTP_PUT},
+		{.str = "append", /* [5] append (CRC = 0xf56e) */
+		 .cmd = HMCDRV_FTP_APPEND},
+		{.str = NULL} /* [6] unused */
+	};
+
+	const struct hmcdrv_ftp_cmd_desc *pdesc;
+
+	u16 crc = 0xffffU;
+
+	if (len == 0)
+		return HMCDRV_FTP_NOOP; /* error indiactor */
+
+	crc = crc16(crc, cmd, len);
+	pdesc = ftpcmds + (crc % ARRAY_SIZE(ftpcmds));
+	pr_debug("FTP command '%s' has CRC 0x%04x, at table pos. %lu\n",
+		 cmd, crc, (crc % ARRAY_SIZE(ftpcmds)));
+
+	if (!pdesc->str || strncmp(pdesc->str, cmd, len))
+		return HMCDRV_FTP_NOOP;
+
+	pr_debug("FTP command '%s' found, with ID %d\n",
+		 pdesc->str, pdesc->cmd);
+
+	return pdesc->cmd;
+}
+
+/**
+ * hmcdrv_ftp_parse() - HMC drive FTP command parser
+ * @cmd: FTP command string "<cmd> <filename>"
+ * @ftp: Pointer to FTP command specification buffer (output)
+ *
+ * Return: 0 on success, else a (negative) error code
+ */
+static int hmcdrv_ftp_parse(char *cmd, struct hmcdrv_ftp_cmdspec *ftp)
+{
+	char *start;
+	int argc = 0;
+
+	ftp->id = HMCDRV_FTP_NOOP;
+	ftp->fname = NULL;
+
+	while (*cmd != '\0') {
+
+		while (isspace(*cmd))
+			++cmd;
+
+		if (*cmd == '\0')
+			break;
+
+		start = cmd;
+
+		switch (argc) {
+		case 0: /* 1st argument (FTP command) */
+			while ((*cmd != '\0') && !isspace(*cmd))
+				++cmd;
+			ftp->id = hmcdrv_ftp_cmd_getid(start, cmd - start);
+			break;
+		case 1: /* 2nd / last argument (rest of line) */
+			while ((*cmd != '\0') && !iscntrl(*cmd))
+				++cmd;
+			ftp->fname = start;
+			/* fall through */
+		default:
+			*cmd = '\0';
+			break;
+		} /* switch */
+
+		++argc;
+	} /* while */
+
+	if (!ftp->fname || (ftp->id == HMCDRV_FTP_NOOP))
+		return -EINVAL;
+
+	return 0;
+}
+
+/**
+ * hmcdrv_ftp_do() - perform a HMC drive FTP, with data from kernel-space
+ * @ftp: pointer to FTP command specification
+ *
+ * Return: number of bytes read/written or a negative error code
+ */
+ssize_t hmcdrv_ftp_do(const struct hmcdrv_ftp_cmdspec *ftp)
+{
+	ssize_t len;
+
+	mutex_lock(&hmcdrv_ftp_mutex);
+
+	if (hmcdrv_ftp_funcs && hmcdrv_ftp_refcnt) {
+		pr_debug("starting transfer, cmd %d for '%s' at %lld with %zd bytes\n",
+			 ftp->id, ftp->fname, (long long) ftp->ofs, ftp->len);
+		len = hmcdrv_cache_cmd(ftp, hmcdrv_ftp_funcs->transfer);
+	} else {
+		len = -ENXIO;
+	}
+
+	mutex_unlock(&hmcdrv_ftp_mutex);
+	return len;
+}
+EXPORT_SYMBOL(hmcdrv_ftp_do);
+
+/**
+ * hmcdrv_ftp_probe() - probe for the HMC drive FTP service
+ *
+ * Return: 0 if service is available, else an (negative) error code
+ */
+int hmcdrv_ftp_probe(void)
+{
+	int rc;
+
+	struct hmcdrv_ftp_cmdspec ftp = {
+		.id = HMCDRV_FTP_NOOP,
+		.ofs = 0,
+		.fname = "",
+		.len = PAGE_SIZE
+	};
+
+	ftp.buf = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+
+	if (!ftp.buf)
+		return -ENOMEM;
+
+	rc = hmcdrv_ftp_startup();
+
+	if (rc)
+		return rc;
+
+	rc = hmcdrv_ftp_do(&ftp);
+	free_page((unsigned long) ftp.buf);
+	hmcdrv_ftp_shutdown();
+
+	switch (rc) {
+	case -ENOENT: /* no such file/media or currently busy, */
+	case -EBUSY:  /* but service seems to be available */
+		rc = 0;
+		break;
+	default: /* leave 'rc' as it is for [0, -EPERM, -E...] */
+		if (rc > 0)
+			rc = 0; /* clear length (success) */
+		break;
+	} /* switch */
+
+	return rc;
+}
+EXPORT_SYMBOL(hmcdrv_ftp_probe);
+
+/**
+ * hmcdrv_ftp_cmd() - Perform a HMC drive FTP, with data from user-space
+ *
+ * @cmd: FTP command string "<cmd> <filename>"
+ * @offset: file position to read/write
+ * @buf: user-space buffer for read/written directory/file
+ * @len: size of @buf (read/dir) or number of bytes to write
+ *
+ * This function must not be called before hmcdrv_ftp_startup() was called.
+ *
+ * Return: number of bytes read/written or a negative error code
+ */
+ssize_t hmcdrv_ftp_cmd(char __kernel *cmd, loff_t offset,
+		       char __user *buf, size_t len)
+{
+	int order;
+
+	struct hmcdrv_ftp_cmdspec ftp = {.len = len, .ofs = offset};
+	ssize_t retlen = hmcdrv_ftp_parse(cmd, &ftp);
+
+	if (retlen)
+		return retlen;
+
+	order = get_order(ftp.len);
+	ftp.buf = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, order);
+
+	if (!ftp.buf)
+		return -ENOMEM;
+
+	switch (ftp.id) {
+	case HMCDRV_FTP_DIR:
+	case HMCDRV_FTP_NLIST:
+	case HMCDRV_FTP_GET:
+		retlen = hmcdrv_ftp_do(&ftp);
+
+		if ((retlen >= 0) &&
+		    copy_to_user(buf, ftp.buf, retlen))
+			retlen = -EFAULT;
+		break;
+
+	case HMCDRV_FTP_PUT:
+	case HMCDRV_FTP_APPEND:
+		if (!copy_from_user(ftp.buf, buf, ftp.len))
+			retlen = hmcdrv_ftp_do(&ftp);
+		else
+			retlen = -EFAULT;
+		break;
+
+	case HMCDRV_FTP_DELETE:
+		retlen = hmcdrv_ftp_do(&ftp);
+		break;
+
+	default:
+		retlen = -EOPNOTSUPP;
+		break;
+	}
+
+	free_pages((unsigned long) ftp.buf, order);
+	return retlen;
+}
+
+/**
+ * hmcdrv_ftp_startup() - startup of HMC drive FTP functionality for a
+ * dedicated (owner) instance
+ *
+ * Return: 0 on success, else an (negative) error code
+ */
+int hmcdrv_ftp_startup(void)
+{
+	static struct hmcdrv_ftp_ops hmcdrv_ftp_zvm = {
+		.startup = diag_ftp_startup,
+		.shutdown = diag_ftp_shutdown,
+		.transfer = diag_ftp_cmd
+	};
+
+	static struct hmcdrv_ftp_ops hmcdrv_ftp_lpar = {
+		.startup = sclp_ftp_startup,
+		.shutdown = sclp_ftp_shutdown,
+		.transfer = sclp_ftp_cmd
+	};
+
+	int rc = 0;
+
+	mutex_lock(&hmcdrv_ftp_mutex); /* block transfers while start-up */
+
+	if (hmcdrv_ftp_refcnt == 0) {
+		if (MACHINE_IS_VM)
+			hmcdrv_ftp_funcs = &hmcdrv_ftp_zvm;
+		else if (MACHINE_IS_LPAR || MACHINE_IS_KVM)
+			hmcdrv_ftp_funcs = &hmcdrv_ftp_lpar;
+		else
+			rc = -EOPNOTSUPP;
+
+		if (hmcdrv_ftp_funcs)
+			rc = hmcdrv_ftp_funcs->startup();
+	}
+
+	if (!rc)
+		++hmcdrv_ftp_refcnt;
+
+	mutex_unlock(&hmcdrv_ftp_mutex);
+	return rc;
+}
+EXPORT_SYMBOL(hmcdrv_ftp_startup);
+
+/**
+ * hmcdrv_ftp_shutdown() - shutdown of HMC drive FTP functionality for a
+ * dedicated (owner) instance
+ */
+void hmcdrv_ftp_shutdown(void)
+{
+	mutex_lock(&hmcdrv_ftp_mutex);
+	--hmcdrv_ftp_refcnt;
+
+	if ((hmcdrv_ftp_refcnt == 0) && hmcdrv_ftp_funcs)
+		hmcdrv_ftp_funcs->shutdown();
+
+	mutex_unlock(&hmcdrv_ftp_mutex);
+}
+EXPORT_SYMBOL(hmcdrv_ftp_shutdown);

drivers/s390/char/hmcdrv_ftp.h

···
+/*
+ *    SE/HMC Drive FTP Services
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ */
+
+#ifndef __HMCDRV_FTP_H__
+#define __HMCDRV_FTP_H__
+
+#include <linux/types.h> /* size_t, loff_t */
+
+/*
+ * HMC drive FTP Service max. length of path (w/ EOS)
+ */
+#define HMCDRV_FTP_FIDENT_MAX 192
+
+/**
+ * enum hmcdrv_ftp_cmdid - HMC drive FTP commands
+ * @HMCDRV_FTP_NOOP: do nothing (only for probing)
+ * @HMCDRV_FTP_GET: read a file
+ * @HMCDRV_FTP_PUT: (over-) write a file
+ * @HMCDRV_FTP_APPEND: append to a file
+ * @HMCDRV_FTP_DIR: list directory long (ls -l)
+ * @HMCDRV_FTP_NLIST: list files, no directories (name list)
+ * @HMCDRV_FTP_DELETE: delete a file
+ * @HMCDRV_FTP_CANCEL: cancel operation (SCLP/LPAR only)
+ */
+enum hmcdrv_ftp_cmdid {
+	HMCDRV_FTP_NOOP = 0,
+	HMCDRV_FTP_GET = 1,
+	HMCDRV_FTP_PUT = 2,
+	HMCDRV_FTP_APPEND = 3,
+	HMCDRV_FTP_DIR = 4,
+	HMCDRV_FTP_NLIST = 5,
+	HMCDRV_FTP_DELETE = 6,
+	HMCDRV_FTP_CANCEL = 7
+};
+
+/**
+ * struct hmcdrv_ftp_cmdspec - FTP command specification
+ * @id: FTP command ID
+ * @ofs: offset in file
+ * @fname: filename (ASCII), null-terminated
+ * @buf: kernel-space transfer data buffer, 4k aligned
+ * @len: (max) number of bytes to transfer from/to @buf
+ */
+struct hmcdrv_ftp_cmdspec {
+	enum hmcdrv_ftp_cmdid id;
+	loff_t ofs;
+	const char *fname;
+	void __kernel *buf;
+	size_t len;
+};
+
+int hmcdrv_ftp_startup(void);
+void hmcdrv_ftp_shutdown(void);
+int hmcdrv_ftp_probe(void);
+ssize_t hmcdrv_ftp_do(const struct hmcdrv_ftp_cmdspec *ftp);
+ssize_t hmcdrv_ftp_cmd(char __kernel *cmd, loff_t offset,
+		       char __user *buf, size_t len);
+
+#endif	 /* __HMCDRV_FTP_H__ */

drivers/s390/char/hmcdrv_mod.c

···
+/*
+ *    HMC Drive DVD Module
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ */
+
+#define KMSG_COMPONENT "hmcdrv"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/version.h>
+#include <linux/stat.h>
+
+#include "hmcdrv_ftp.h"
+#include "hmcdrv_dev.h"
+#include "hmcdrv_cache.h"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Copyright 2013 IBM Corporation");
+MODULE_DESCRIPTION("HMC drive DVD access");
+
+/*
+ * module parameter 'cachesize'
+ */
+static size_t hmcdrv_mod_cachesize = HMCDRV_CACHE_SIZE_DFLT;
+module_param_named(cachesize, hmcdrv_mod_cachesize, ulong, S_IRUGO);
+
+/**
+ * hmcdrv_mod_init() - module init function
+ */
+static int __init hmcdrv_mod_init(void)
+{
+	int rc = hmcdrv_ftp_probe(); /* perform w/o cache */
+
+	if (rc)
+		return rc;
+
+	rc = hmcdrv_cache_startup(hmcdrv_mod_cachesize);
+
+	if (rc)
+		return rc;
+
+	rc = hmcdrv_dev_init();
+
+	if (rc)
+		hmcdrv_cache_shutdown();
+
+	return rc;
+}
+
+/**
+ * hmcdrv_mod_exit() - module exit function
+ */
+static void __exit hmcdrv_mod_exit(void)
+{
+	hmcdrv_dev_exit();
+	hmcdrv_cache_shutdown();
+}
+
+module_init(hmcdrv_mod_init);
+module_exit(hmcdrv_mod_exit);

drivers/s390/char/sclp.h

···
 
 #define EVTYP_OPCMD		0x01
 #define EVTYP_MSG		0x02
+#define EVTYP_DIAG_TEST		0x07
 #define EVTYP_STATECHANGE	0x08
 #define EVTYP_PMSGCMD		0x09
 #define EVTYP_CNTLPROGOPCMD	0x20
···
 
 #define EVTYP_OPCMD_MASK	0x80000000
 #define EVTYP_MSG_MASK		0x40000000
+#define EVTYP_DIAG_TEST_MASK	0x02000000
 #define EVTYP_STATECHANGE_MASK	0x01000000
 #define EVTYP_PMSGCMD_MASK	0x00800000
 #define EVTYP_CTLPROGOPCMD_MASK	0x00000001

drivers/s390/char/sclp_diag.h

···
+/*
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ */
+
+#ifndef _SCLP_DIAG_H
+#define _SCLP_DIAG_H
+
+#include <linux/types.h>
+
+/* return codes for Diagnostic Test FTP Service, as indicated in member
+ * sclp_diag_ftp::ldflg
+ */
+#define SCLP_DIAG_FTP_OK	0x80U /* success */
+#define SCLP_DIAG_FTP_LDFAIL	0x01U /* load failed */
+#define SCLP_DIAG_FTP_LDNPERM	0x02U /* not allowed */
+#define SCLP_DIAG_FTP_LDRUNS	0x03U /* LD runs */
+#define SCLP_DIAG_FTP_LDNRUNS	0x04U /* LD does not run */
+
+#define SCLP_DIAG_FTP_XPCX	0x80 /* PCX communication code */
+#define SCLP_DIAG_FTP_ROUTE	4 /* routing code for new FTP service */
+
+/*
+ * length of Diagnostic Test FTP Service event buffer
+ */
+#define SCLP_DIAG_FTP_EVBUF_LEN				\
+	(offsetof(struct sclp_diag_evbuf, mdd) +	\
+	 sizeof(struct sclp_diag_ftp))
+
+/**
+ * struct sclp_diag_ftp - Diagnostic Test FTP Service model-dependent data
+ * @pcx: code for PCX communication (should be 0x80)
+ * @ldflg: load flag (see defines above)
+ * @cmd: FTP command
+ * @pgsize: page size (0 = 4kB, 1 = large page size)
+ * @srcflg: source flag
+ * @spare: reserved (zeroes)
+ * @offset: file offset
+ * @fsize: file size
+ * @length: buffer size resp. bytes transferred
+ * @failaddr: failing address
+ * @bufaddr: buffer address, virtual
+ * @asce: region or segment table designation
+ * @fident: file name (ASCII, zero-terminated)
+ */
+struct sclp_diag_ftp {
+	u8 pcx;
+	u8 ldflg;
+	u8 cmd;
+	u8 pgsize;
+	u8 srcflg;
+	u8 spare;
+	u64 offset;
+	u64 fsize;
+	u64 length;
+	u64 failaddr;
+	u64 bufaddr;
+	u64 asce;
+
+	u8 fident[256];
+} __packed;
+
+/**
+ * struct sclp_diag_evbuf - Diagnostic Test (ET7) Event Buffer
+ * @hdr: event buffer header
+ * @route: diagnostic route
+ * @mdd: model-dependent data (@route dependent)
+ */
+struct sclp_diag_evbuf {
+	struct evbuf_header hdr;
+	u16 route;
+
+	union {
+		struct sclp_diag_ftp ftp;
+	} mdd;
+} __packed;
+
+/**
+ * struct sclp_diag_sccb - Diagnostic Test (ET7) SCCB
+ * @hdr: SCCB header
+ * @evbuf: event buffer
+ */
+struct sclp_diag_sccb {
+
+	struct sccb_header hdr;
+	struct sclp_diag_evbuf evbuf;
+} __packed;
+
+#endif /* _SCLP_DIAG_H */

drivers/s390/char/sclp_ftp.c

···
+/*
+ *    SCLP Event Type (ET) 7 - Diagnostic Test FTP Services, useable on LPAR
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ *
+ */
+
+#define KMSG_COMPONENT "hmcdrv"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/wait.h>
+#include <linux/string.h>
+#include <linux/jiffies.h>
+#include <asm/sysinfo.h>
+#include <asm/ebcdic.h>
+
+#include "sclp.h"
+#include "sclp_diag.h"
+#include "sclp_ftp.h"
+
+static DECLARE_COMPLETION(sclp_ftp_rx_complete);
+static u8 sclp_ftp_ldflg;
+static u64 sclp_ftp_fsize;
+static u64 sclp_ftp_length;
+
+/**
+ * sclp_ftp_txcb() - Diagnostic Test FTP services SCLP command callback
+ */
+static void sclp_ftp_txcb(struct sclp_req *req, void *data)
+{
+	struct completion *completion = data;
+
+#ifdef DEBUG
+	pr_debug("SCLP (ET7) TX-IRQ, SCCB @ 0x%p: %*phN\n",
+		 req->sccb, 24, req->sccb);
+#endif
+	complete(completion);
+}
+
+/**
+ * sclp_ftp_rxcb() - Diagnostic Test FTP services receiver event callback
+ */
+static void sclp_ftp_rxcb(struct evbuf_header *evbuf)
+{
+	struct sclp_diag_evbuf *diag = (struct sclp_diag_evbuf *) evbuf;
+
+	/*
+	 * Check for Diagnostic Test FTP Service
+	 */
+	if (evbuf->type != EVTYP_DIAG_TEST ||
+	    diag->route != SCLP_DIAG_FTP_ROUTE ||
+	    diag->mdd.ftp.pcx != SCLP_DIAG_FTP_XPCX ||
+	    evbuf->length < SCLP_DIAG_FTP_EVBUF_LEN)
+		return;
+
+#ifdef DEBUG
+	pr_debug("SCLP (ET7) RX-IRQ, Event @ 0x%p: %*phN\n",
+		 evbuf, 24, evbuf);
+#endif
+
+	/*
+	 * Because the event buffer is located in a page which is owned
+	 * by the SCLP core, all data of interest must be copied. The
+	 * error indication is in 'sclp_ftp_ldflg'
+	 */
+	sclp_ftp_ldflg = diag->mdd.ftp.ldflg;
+	sclp_ftp_fsize = diag->mdd.ftp.fsize;
+	sclp_ftp_length = diag->mdd.ftp.length;
+
+	complete(&sclp_ftp_rx_complete);
+}
+
+/**
+ * sclp_ftp_et7() - start a Diagnostic Test FTP Service SCLP request
+ * @ftp: pointer to FTP descriptor
+ *
+ * Return: 0 on success, else a (negative) error code
+ */
+static int sclp_ftp_et7(const struct hmcdrv_ftp_cmdspec *ftp)
+{
+	struct completion completion;
+	struct sclp_diag_sccb *sccb;
+	struct sclp_req *req;
+	size_t len;
+	int rc;
+
+	req = kzalloc(sizeof(*req), GFP_KERNEL);
+	sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!req || !sccb) {
+		rc = -ENOMEM;
+		goto out_free;
+	}
+
+	sccb->hdr.length = SCLP_DIAG_FTP_EVBUF_LEN +
+		sizeof(struct sccb_header);
+	sccb->evbuf.hdr.type = EVTYP_DIAG_TEST;
+	sccb->evbuf.hdr.length = SCLP_DIAG_FTP_EVBUF_LEN;
+	sccb->evbuf.hdr.flags = 0; /* clear processed-buffer */
+	sccb->evbuf.route = SCLP_DIAG_FTP_ROUTE;
+	sccb->evbuf.mdd.ftp.pcx = SCLP_DIAG_FTP_XPCX;
+	sccb->evbuf.mdd.ftp.srcflg = 0;
+	sccb->evbuf.mdd.ftp.pgsize = 0;
+	sccb->evbuf.mdd.ftp.asce = _ASCE_REAL_SPACE;
+	sccb->evbuf.mdd.ftp.ldflg = SCLP_DIAG_FTP_LDFAIL;
+	sccb->evbuf.mdd.ftp.fsize = 0;
+	sccb->evbuf.mdd.ftp.cmd = ftp->id;
+	sccb->evbuf.mdd.ftp.offset = ftp->ofs;
+	sccb->evbuf.mdd.ftp.length = ftp->len;
+	sccb->evbuf.mdd.ftp.bufaddr = virt_to_phys(ftp->buf);
+
+	len = strlcpy(sccb->evbuf.mdd.ftp.fident, ftp->fname,
+		      HMCDRV_FTP_FIDENT_MAX);
+	if (len >= HMCDRV_FTP_FIDENT_MAX) {
+		rc = -EINVAL;
+		goto out_free;
+	}
+
+	req->command = SCLP_CMDW_WRITE_EVENT_DATA;
+	req->sccb = sccb;
+	req->status = SCLP_REQ_FILLED;
+	req->callback = sclp_ftp_txcb;
+	req->callback_data = &completion;
+
+	init_completion(&completion);
+
+	rc = sclp_add_request(req);
+	if (rc)
+		goto out_free;
+
+	/* Wait for end of ftp sclp command. */
+	wait_for_completion(&completion);
+
+#ifdef DEBUG
+	pr_debug("status of SCLP (ET7) request is 0x%04x (0x%02x)\n",
+		 sccb->hdr.response_code, sccb->evbuf.hdr.flags);
+#endif
+
+	/*
+	 * Check if sclp accepted the request. The data transfer runs
+	 * asynchronously and the completion is indicated with an
+	 * sclp ET7 event.
+	 */
+	if (req->status != SCLP_REQ_DONE ||
+	    (sccb->evbuf.hdr.flags & 0x80) == 0 || /* processed-buffer */
+	    (sccb->hdr.response_code & 0xffU) != 0x20U) {
+		rc = -EIO;
+	}
+
+out_free:
+	free_page((unsigned long) sccb);
+	kfree(req);
+	return rc;
+}
+
+/**
+ * sclp_ftp_cmd() - executes a HMC related SCLP Diagnose (ET7) FTP command
+ * @ftp: pointer to FTP command specification
+ * @fsize: return of file size (or NULL if undesirable)
+ *
+ * Attention: Notice that this function is not reentrant - so the caller
+ * must ensure locking.
+ *
+ * Return: number of bytes read/written or a (negative) error code
+ */
+ssize_t sclp_ftp_cmd(const struct hmcdrv_ftp_cmdspec *ftp, size_t *fsize)
+{
+	ssize_t len;
+#ifdef DEBUG
+	unsigned long start_jiffies;
+
+	pr_debug("starting SCLP (ET7), cmd %d for '%s' at %lld with %zd bytes\n",
+		 ftp->id, ftp->fname, (long long) ftp->ofs, ftp->len);
+	start_jiffies = jiffies;
+#endif
+
+	init_completion(&sclp_ftp_rx_complete);
+
+	/* Start ftp sclp command. */
+	len = sclp_ftp_et7(ftp);
+	if (len)
+		goto out_unlock;
+
+	/*
+	 * There is no way to cancel the sclp ET7 request, the code
+	 * needs to wait unconditionally until the transfer is complete.
+	 */
+	wait_for_completion(&sclp_ftp_rx_complete);
+
+#ifdef DEBUG
+	pr_debug("completed SCLP (ET7) request after %lu ms (all)\n",
+		 (jiffies - start_jiffies) * 1000 / HZ);
+	pr_debug("return code of SCLP (ET7) FTP Service is 0x%02x, with %lld/%lld bytes\n",
+		 sclp_ftp_ldflg, sclp_ftp_length, sclp_ftp_fsize);
+#endif
+
+	switch (sclp_ftp_ldflg) {
+	case SCLP_DIAG_FTP_OK:
+		len = sclp_ftp_length;
+		if (fsize)
+			*fsize = sclp_ftp_fsize;
+		break;
+	case SCLP_DIAG_FTP_LDNPERM:
+		len = -EPERM;
+		break;
+	case SCLP_DIAG_FTP_LDRUNS:
+		len = -EBUSY;
+		break;
+	case SCLP_DIAG_FTP_LDFAIL:
+		len = -ENOENT;
+		break;
+	default:
+		len = -EIO;
+		break;
+	}
+
+out_unlock:
+	return len;
+}
+
+/*
+ * ET7 event listener
+ */
+static struct sclp_register sclp_ftp_event = {
+	.send_mask = EVTYP_DIAG_TEST_MASK,    /* want tx events */
+	.receive_mask = EVTYP_DIAG_TEST_MASK, /* want rx events */
+	.receiver_fn = sclp_ftp_rxcb,	      /* async callback (rx) */
+	.state_change_fn = NULL,
+	.pm_event_fn = NULL,
+};
+
+/**
+ * sclp_ftp_startup() - startup of FTP services, when running on LPAR
+ */
+int sclp_ftp_startup(void)
+{
+#ifdef DEBUG
+	unsigned long info;
+#endif
+	int rc;
+
+	rc = sclp_register(&sclp_ftp_event);
+	if (rc)
+		return rc;
+
+#ifdef DEBUG
+	info = get_zeroed_page(GFP_KERNEL);
+
+	if (info != 0) {
+		struct sysinfo_2_2_2 *info222 = (struct sysinfo_2_2_2 *)info;
+
+		if (!stsi(info222, 2, 2, 2)) { /* get SYSIB 2.2.2 */
+			info222->name[sizeof(info222->name) - 1] = '\0';
+			EBCASC_500(info222->name, sizeof(info222->name) - 1);
+			pr_debug("SCLP (ET7) FTP Service working on LPAR %u (%s)\n",
+				 info222->lpar_number, info222->name);
+		}
+
+		free_page(info);
+	}
+#endif	/* DEBUG */
+	return 0;
+}
+
+/**
+ * sclp_ftp_shutdown() - shutdown of FTP services, when running on LPAR
+ */
+void sclp_ftp_shutdown(void)
+{
+	sclp_unregister(&sclp_ftp_event);
+}

drivers/s390/char/sclp_ftp.h

···
+/*
+ *    SCLP Event Type (ET) 7 - Diagnostic Test FTP Services, useable on LPAR
+ *
+ *    Notice that all functions exported here are not reentrant.
+ *    So usage should be exclusive, ensured by the caller (e.g. using a
+ *    mutex).
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Ralf Hoppe ([e-mail])
+ */
+
+#ifndef __SCLP_FTP_H__
+#define __SCLP_FTP_H__
+
+#include "hmcdrv_ftp.h"
+
+int sclp_ftp_startup(void);
+void sclp_ftp_shutdown(void);
+ssize_t sclp_ftp_cmd(const struct hmcdrv_ftp_cmdspec *ftp, size_t *fsize);
+
+#endif	 /* __SCLP_FTP_H__ */