sdio: core support for SDIO function interrupt

Signed-off-by: Nicolas Pitre <[e-mail]>
Signed-off-by: Pierre Ossman <[e-mail]>

drivers/mmc/core/Makefile

···
 mmc_core-y			:= core.o sysfs.o bus.o host.o \
 				   mmc.o mmc_ops.o sd.o sd_ops.o \
 				   sdio.o sdio_ops.o sdio_bus.o \
-				   sdio_cis.o sdio_io.o
+				   sdio_cis.o sdio_io.o sdio_irq.o
 

drivers/mmc/core/sdio_bus.c

···
 
 	drv->remove(func);
 
+	if (func->irq_handler) {
+		printk(KERN_WARNING "WARNING: driver %s did not remove "
+			"its interrupt handler!\n", drv->name);
+		sdio_claim_host(func);
+		sdio_release_irq(func);
+		sdio_release_host(func);
+	}
+
 	return 0;
 }
 

drivers/mmc/core/sdio_irq.c

···
+/*
+ * linux/drivers/mmc/core/sdio_irq.c
+ *
+ * Author:      Nicolas Pitre
+ * Created:     June 18, 2007
+ * Copyright:   MontaVista Software Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/kthread.h>
+#include <linux/wait.h>
+#include <linux/delay.h>
+
+#include <linux/mmc/core.h>
+#include <linux/mmc/host.h>
+#include <linux/mmc/card.h>
+#include <linux/mmc/sdio.h>
+#include <linux/mmc/sdio_func.h>
+
+#include "sdio_ops.h"
+
+static int process_sdio_pending_irqs(struct mmc_card *card)
+{
+	int i, ret;
+	unsigned char pending;
+
+	ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_INTx, 0, &pending);
+	if (ret) {
+		printk(KERN_DEBUG "%s: error %d reading SDIO_CCCR_INTx\n",
+		       mmc_card_id(card), ret);
+		return ret;
+	}
+
+	for (i = 1; i <= 7; i++) {
+		if (pending & (1 << i)) {
+			struct sdio_func *func = card->sdio_func[i - 1];
+			if (!func) {
+				printk(KERN_WARNING "%s: pending IRQ for "
+					"non-existant function\n",
+					sdio_func_id(func));
+			} else if (func->irq_handler) {
+				func->irq_handler(func);
+			} else
+				printk(KERN_WARNING "%s: pending IRQ with no handler\n",
+				       sdio_func_id(func));
+		}
+	}
+
+	return 0;
+}
+
+static int sdio_irq_thread(void *_host)
+{
+	struct mmc_host *host = _host;
+	struct sched_param param = { .sched_priority = 1 };
+	unsigned long period;
+	int ret;
+
+	sched_setscheduler(current, SCHED_FIFO, &param);
+
+	/*
+	 * We want to allow for SDIO cards to work even on non SDIO
+	 * aware hosts.  One thing that non SDIO host cannot do is
+	 * asynchronous notification of pending SDIO card interrupts
+	 * hence we poll for them in that case.
+	 */
+	period = msecs_to_jiffies(10);
+
+	pr_debug("%s: IRQ thread started (poll period = %lu jiffies)\n",
+		 mmc_hostname(host), period);
+
+	do {
+		/*
+		 * We claim the host here on drivers behalf for a couple
+		 * reasons:
+		 *
+		 * 1) it is already needed to retrieve the CCCR_INTx;
+		 * 2) we want the driver(s) to clear the IRQ condition ASAP;
+		 * 3) we need to control the abort condition locally.
+		 *
+		 * Just like traditional hard IRQ handlers, we expect SDIO
+		 * IRQ handlers to be quick and to the point, so that the
+		 * holding of the host lock does not cover too much work
+		 * that doesn't require that lock to be held.
+		 */
+		ret = __mmc_claim_host(host, &host->sdio_irq_thread_abort);
+		if (ret)
+			break;
+		ret = process_sdio_pending_irqs(host->card);
+		mmc_release_host(host);
+
+		/*
+		 * Give other threads a chance to run in the presence of
+		 * errors.  FIXME: determine if due to card removal and
+		 * possibly exit this thread if so.
+		 */
+		if (ret)
+			ssleep(1);
+
+		set_task_state(current, TASK_INTERRUPTIBLE);
+		if (!kthread_should_stop())
+			schedule_timeout(period);
+		set_task_state(current, TASK_RUNNING);
+	} while (!kthread_should_stop());
+
+	pr_debug("%s: IRQ thread exiting with code %d\n",
+		 mmc_hostname(host), ret);
+
+	return ret;
+}
+
+static int sdio_card_irq_get(struct mmc_card *card)
+{
+	struct mmc_host *host = card->host;
+
+	BUG_ON(!host->claimed);
+
+	if (!host->sdio_irqs++) {
+		atomic_set(&host->sdio_irq_thread_abort, 0);
+		host->sdio_irq_thread =
+			kthread_run(sdio_irq_thread, host, "ksdiorqd");
+		if (IS_ERR(host->sdio_irq_thread)) {
+			int err = PTR_ERR(host->sdio_irq_thread);
+			host->sdio_irqs--;
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int sdio_card_irq_put(struct mmc_card *card)
+{
+	struct mmc_host *host = card->host;
+
+	BUG_ON(!host->claimed);
+	BUG_ON(host->sdio_irqs < 1);
+
+	if (!--host->sdio_irqs) {
+		atomic_set(&host->sdio_irq_thread_abort, 1);
+		kthread_stop(host->sdio_irq_thread);
+	}
+
+	return 0;
+}
+
+/**
+ *	sdio_claim_irq - claim the IRQ for a SDIO function
+ *	@func: SDIO function
+ *	@handler: IRQ handler callback
+ *
+ *	Claim and activate the IRQ for the given SDIO function. The provided
+ *	handler will be called when that IRQ is asserted.  The host is always
+ *	claimed already when the handler is called so the handler must not
+ *	call sdio_claim_host() nor sdio_release_host().
+ */
+int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler)
+{
+	int ret;
+	unsigned char reg;
+
+	BUG_ON(!func);
+	BUG_ON(!func->card);
+
+	pr_debug("SDIO: Enabling IRQ for %s...\n", sdio_func_id(func));
+
+	if (func->irq_handler) {
+		pr_debug("SDIO: IRQ for %s already in use.\n", sdio_func_id(func));
+		return -EBUSY;
+	}
+
+	ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, &reg);
+	if (ret)
+		return ret;
+
+	reg |= 1 << func->num;
+
+	reg |= 1; /* Master interrupt enable */
+
+	ret = mmc_io_rw_direct(func->card, 1, 0, SDIO_CCCR_IENx, reg, NULL);
+	if (ret)
+		return ret;
+
+	func->irq_handler = handler;
+	ret = sdio_card_irq_get(func->card);
+	if (ret)
+		func->irq_handler = NULL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sdio_claim_irq);
+
+/**
+ *	sdio_release_irq - release the IRQ for a SDIO function
+ *	@func: SDIO function
+ *
+ *	Disable and release the IRQ for the given SDIO function.
+ */
+int sdio_release_irq(struct sdio_func *func)
+{
+	int ret;
+	unsigned char reg;
+
+	BUG_ON(!func);
+	BUG_ON(!func->card);
+
+	pr_debug("SDIO: Disabling IRQ for %s...\n", sdio_func_id(func));
+
+	if (func->irq_handler) {
+		func->irq_handler = NULL;
+		sdio_card_irq_put(func->card);
+	}
+
+	ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, &reg);
+	if (ret)
+		return ret;
+
+	reg &= ~(1 << func->num);
+
+	/* Disable master interrupt with the last function interrupt */
+	if (!(reg & 0xFE))
+		reg = 0;
+
+	ret = mmc_io_rw_direct(func->card, 1, 0, SDIO_CCCR_IENx, reg, NULL);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sdio_release_irq);
+

include/linux/mmc/host.h

···
 	unsigned int		bus_refs;	/* reference counter */
 	unsigned int		bus_dead:1;	/* bus has been released */
 
+	unsigned int		sdio_irqs;
+	struct task_struct	*sdio_irq_thread;
+	atomic_t		sdio_irq_thread_abort;
+
 	unsigned long		private[0] ____cacheline_aligned;
 };
 

include/linux/mmc/sdio_func.h

···
 #include <linux/mod_devicetable.h>
 
 struct mmc_card;
+struct sdio_func;
+
+typedef void (sdio_irq_handler_t)(struct sdio_func *);
 
 /*
  * SDIO function CIS tuple (unknown to the core)
···
 struct sdio_func {
 	struct mmc_card		*card;		/* the card this device belongs to */
 	struct device		dev;		/* the device */
+	sdio_irq_handler_t	*irq_handler;	/* IRQ callback */
 	unsigned int		num;		/* function number */
 
 	unsigned char		class;		/* standard interface class */
···
 
 extern int sdio_enable_func(struct sdio_func *func);
 extern int sdio_disable_func(struct sdio_func *func);
+
+extern int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler);
+extern int sdio_release_irq(struct sdio_func *func);
 
 extern unsigned char sdio_readb(struct sdio_func *func,
 	unsigned int addr, int *err_ret);