[PATCH] S3C24XX: hardware SPI driver

Hardware based SPI driver for Samsung S3C24XX SoC systems

Signed-off-by: Ben Dooks <[e-mail]>
Cc: David Brownell <[e-mail]>
Cc: Greg KH <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/spi/Kconfig

···
 #
 
 
+config SPI_S3C24XX
+	tristate "Samsung S3C24XX series SPI"
+	depends on SPI_MASTER && ARCH_S3C2410 && EXPERIMENTAL
+	help
+	  SPI driver for Samsung S3C24XX series ARM SoCs
+
 #
 # There are lots of SPI device types, with sensors and memory
 # being probably the most widely used ones.

drivers/spi/Makefile

···
 obj-$(CONFIG_SPI_PXA2XX)		+= pxa2xx_spi.o
 obj-$(CONFIG_SPI_MPC83xx)		+= spi_mpc83xx.o
 obj-$(CONFIG_SPI_S3C24XX_GPIO)		+= spi_s3c24xx_gpio.o
+obj-$(CONFIG_SPI_S3C24XX)		+= spi_s3c24xx.o
 # 	... add above this line ...
 
 # SPI protocol drivers (device/link on bus)

drivers/spi/spi_s3c24xx.c

···
+/* linux/drivers/spi/spi_s3c24xx.c
+ *
+ * Copyright (c) 2006 Ben Dooks
+ * Copyright (c) 2006 Simtec Electronics
+ *	Ben Dooks <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+*/
+
+
+//#define DEBUG
+
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+#include <asm/io.h>
+#include <asm/dma.h>
+#include <asm/hardware.h>
+
+#include <asm/arch/regs-gpio.h>
+#include <asm/arch/regs-spi.h>
+#include <asm/arch/spi.h>
+
+struct s3c24xx_spi {
+	/* bitbang has to be first */
+	struct spi_bitbang	 bitbang;
+	struct completion	 done;
+
+	void __iomem		*regs;
+	int			 irq;
+	int			 len;
+	int			 count;
+
+	/* data buffers */
+	const unsigned char	*tx;
+	unsigned char		*rx;
+
+	struct clk		*clk;
+	struct resource		*ioarea;
+	struct spi_master	*master;
+	struct spi_device	*curdev;
+	struct device		*dev;
+	struct s3c2410_spi_info *pdata;
+};
+
+#define SPCON_DEFAULT (S3C2410_SPCON_MSTR | S3C2410_SPCON_SMOD_INT)
+#define SPPIN_DEFAULT (S3C2410_SPPIN_KEEP)
+
+static inline struct s3c24xx_spi *to_hw(struct spi_device *sdev)
+{
+	return spi_master_get_devdata(sdev->master);
+}
+
+static void s3c24xx_spi_chipsel(struct spi_device *spi, int value)
+{
+	struct s3c24xx_spi *hw = to_hw(spi);
+	unsigned int cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
+	unsigned int spcon;
+
+	switch (value) {
+	case BITBANG_CS_INACTIVE:
+		if (hw->pdata->set_cs)
+			hw->pdata->set_cs(hw->pdata, value, cspol);
+		else
+			s3c2410_gpio_setpin(hw->pdata->pin_cs, cspol ^ 1);
+		break;
+
+	case BITBANG_CS_ACTIVE:
+		spcon = readb(hw->regs + S3C2410_SPCON);
+
+		if (spi->mode & SPI_CPHA)
+			spcon |= S3C2410_SPCON_CPHA_FMTB;
+		else
+			spcon &= ~S3C2410_SPCON_CPHA_FMTB;
+
+		if (spi->mode & SPI_CPOL)
+			spcon |= S3C2410_SPCON_CPOL_HIGH;
+		else
+			spcon &= ~S3C2410_SPCON_CPOL_HIGH;
+
+		spcon |= S3C2410_SPCON_ENSCK;
+
+		/* write new configration */
+
+		writeb(spcon, hw->regs + S3C2410_SPCON);
+
+		if (hw->pdata->set_cs)
+			hw->pdata->set_cs(hw->pdata, value, cspol);
+		else
+			s3c2410_gpio_setpin(hw->pdata->pin_cs, cspol);
+
+		break;
+
+	}
+}
+
+static int s3c24xx_spi_setupxfer(struct spi_device *spi,
+				 struct spi_transfer *t)
+{
+	struct s3c24xx_spi *hw = to_hw(spi);
+	unsigned int bpw;
+	unsigned int hz;
+	unsigned int div;
+
+	bpw = t ? t->bits_per_word : spi->bits_per_word;
+	hz  = t ? t->speed_hz : spi->max_speed_hz;
+
+	if (bpw != 8) {
+		dev_err(&spi->dev, "invalid bits-per-word (%d)\n", bpw);
+		return -EINVAL;
+	}
+
+	div = clk_get_rate(hw->clk) / hz;
+
+	/* is clk = pclk / (2 * (pre+1)), or is it
+	 *    clk = (pclk * 2) / ( pre + 1) */
+
+	div = (div / 2) - 1;
+
+	if (div < 0)
+		div = 1;
+
+	if (div > 255)
+		div = 255;
+
+	dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", div, hz);
+	writeb(div, hw->regs + S3C2410_SPPRE);
+
+	spin_lock(&hw->bitbang.lock);
+	if (!hw->bitbang.busy) {
+		hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
+		/* need to ndelay for 0.5 clocktick ? */
+	}
+	spin_unlock(&hw->bitbang.lock);
+
+	return 0;
+}
+
+static int s3c24xx_spi_setup(struct spi_device *spi)
+{
+	int ret;
+
+	if (!spi->bits_per_word)
+		spi->bits_per_word = 8;
+
+	if ((spi->mode & SPI_LSB_FIRST) != 0)
+		return -EINVAL;
+
+	ret = s3c24xx_spi_setupxfer(spi, NULL);
+	if (ret < 0) {
+		dev_err(&spi->dev, "setupxfer returned %d\n", ret);
+		return ret;
+	}
+
+	dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n",
+		__FUNCTION__, spi->mode, spi->bits_per_word,
+		spi->max_speed_hz);
+
+	return 0;
+}
+
+static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count)
+{
+	return hw->tx ? hw->tx[count] : 0xff;
+}
+
+static int s3c24xx_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct s3c24xx_spi *hw = to_hw(spi);
+
+	dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
+		t->tx_buf, t->rx_buf, t->len);
+
+	hw->tx = t->tx_buf;
+	hw->rx = t->rx_buf;
+	hw->len = t->len;
+	hw->count = 0;
+
+	/* send the first byte */
+	writeb(hw_txbyte(hw, 0), hw->regs + S3C2410_SPTDAT);
+	wait_for_completion(&hw->done);
+
+	return hw->count;
+}
+
+static irqreturn_t s3c24xx_spi_irq(int irq, void *dev, struct pt_regs *regs)
+{
+	struct s3c24xx_spi *hw = dev;
+	unsigned int spsta = readb(hw->regs + S3C2410_SPSTA);
+	unsigned int count = hw->count;
+
+	if (spsta & S3C2410_SPSTA_DCOL) {
+		dev_dbg(hw->dev, "data-collision\n");
+		complete(&hw->done);
+		goto irq_done;
+	}
+
+	if (!(spsta & S3C2410_SPSTA_READY)) {
+		dev_dbg(hw->dev, "spi not ready for tx?\n");
+		complete(&hw->done);
+		goto irq_done;
+	}
+
+	hw->count++;
+
+	if (hw->rx)
+		hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);
+
+	count++;
+
+	if (count < hw->len)
+		writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
+	else
+		complete(&hw->done);
+
+ irq_done:
+	return IRQ_HANDLED;
+}
+
+static int s3c24xx_spi_probe(struct platform_device *pdev)
+{
+	struct s3c24xx_spi *hw;
+	struct spi_master *master;
+	struct spi_board_info *bi;
+	struct resource *res;
+	int err = 0;
+	int i;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct s3c24xx_spi));
+	if (master == NULL) {
+		dev_err(&pdev->dev, "No memory for spi_master\n");
+		err = -ENOMEM;
+		goto err_nomem;
+	}
+
+	hw = spi_master_get_devdata(master);
+	memset(hw, 0, sizeof(struct s3c24xx_spi));
+
+	hw->master = spi_master_get(master);
+	hw->pdata = pdev->dev.platform_data;
+	hw->dev = &pdev->dev;
+
+	if (hw->pdata == NULL) {
+		dev_err(&pdev->dev, "No platform data supplied\n");
+		err = -ENOENT;
+		goto err_no_pdata;
+	}
+
+	platform_set_drvdata(pdev, hw);
+	init_completion(&hw->done);
+
+	/* setup the state for the bitbang driver */
+
+	hw->bitbang.master         = hw->master;
+	hw->bitbang.setup_transfer = s3c24xx_spi_setupxfer;
+	hw->bitbang.chipselect     = s3c24xx_spi_chipsel;
+	hw->bitbang.txrx_bufs      = s3c24xx_spi_txrx;
+	hw->bitbang.master->setup  = s3c24xx_spi_setup;
+
+	dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang);
+
+	/* find and map our resources */
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(&pdev->dev, "Cannot get IORESOURCE_MEM\n");
+		err = -ENOENT;
+		goto err_no_iores;
+	}
+
+	hw->ioarea = request_mem_region(res->start, (res->end - res->start)+1,
+					pdev->name);
+
+	if (hw->ioarea == NULL) {
+		dev_err(&pdev->dev, "Cannot reserve region\n");
+		err = -ENXIO;
+		goto err_no_iores;
+	}
+
+	hw->regs = ioremap(res->start, (res->end - res->start)+1);
+	if (hw->regs == NULL) {
+		dev_err(&pdev->dev, "Cannot map IO\n");
+		err = -ENXIO;
+		goto err_no_iomap;
+	}
+
+	hw->irq = platform_get_irq(pdev, 0);
+	if (hw->irq < 0) {
+		dev_err(&pdev->dev, "No IRQ specified\n");
+		err = -ENOENT;
+		goto err_no_irq;
+	}
+
+	err = request_irq(hw->irq, s3c24xx_spi_irq, 0, pdev->name, hw);
+	if (err) {
+		dev_err(&pdev->dev, "Cannot claim IRQ\n");
+		goto err_no_irq;
+	}
+
+	hw->clk = clk_get(&pdev->dev, "spi");
+	if (IS_ERR(hw->clk)) {
+		dev_err(&pdev->dev, "No clock for device\n");
+		err = PTR_ERR(hw->clk);
+		goto err_no_clk;
+	}
+
+	/* for the moment, permanently enable the clock */
+
+	clk_enable(hw->clk);
+
+	/* program defaults into the registers */
+
+	writeb(0xff, hw->regs + S3C2410_SPPRE);
+	writeb(SPPIN_DEFAULT, hw->regs + S3C2410_SPPIN);
+	writeb(SPCON_DEFAULT, hw->regs + S3C2410_SPCON);
+
+	/* setup any gpio we can */
+
+	if (!hw->pdata->set_cs) {
+		s3c2410_gpio_setpin(hw->pdata->pin_cs, 1);
+		s3c2410_gpio_cfgpin(hw->pdata->pin_cs, S3C2410_GPIO_OUTPUT);
+	}
+
+	/* register our spi controller */
+
+	err = spi_bitbang_start(&hw->bitbang);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to register SPI master\n");
+		goto err_register;
+	}
+
+	dev_dbg(hw->dev, "shutdown=%d\n", hw->bitbang.shutdown);
+
+	/* register all the devices associated */
+
+	bi = &hw->pdata->board_info[0];
+	for (i = 0; i < hw->pdata->board_size; i++, bi++) {
+		dev_info(hw->dev, "registering %s\n", bi->modalias);
+
+		bi->controller_data = hw;
+		spi_new_device(master, bi);
+	}
+
+	return 0;
+
+ err_register:
+	clk_disable(hw->clk);
+	clk_put(hw->clk);
+
+ err_no_clk:
+	free_irq(hw->irq, hw);
+
+ err_no_irq:
+	iounmap(hw->regs);
+
+ err_no_iomap:
+	release_resource(hw->ioarea);
+	kfree(hw->ioarea);
+
+ err_no_iores:
+ err_no_pdata:
+	spi_master_put(hw->master);;
+
+ err_nomem:
+	return err;
+}
+
+static int s3c24xx_spi_remove(struct platform_device *dev)
+{
+	struct s3c24xx_spi *hw = platform_get_drvdata(dev);
+
+	platform_set_drvdata(dev, NULL);
+
+	spi_unregister_master(hw->master);
+
+	clk_disable(hw->clk);
+	clk_put(hw->clk);
+
+	free_irq(hw->irq, hw);
+	iounmap(hw->regs);
+
+	release_resource(hw->ioarea);
+	kfree(hw->ioarea);
+
+	spi_master_put(hw->master);
+	return 0;
+}
+
+
+#ifdef CONFIG_PM
+
+static int s3c24xx_spi_suspend(struct platform_device *pdev, pm_message_t msg)
+{
+	struct s3c24xx_spi *hw = platform_get_drvdata(dev);
+
+	clk_disable(hw->clk);
+	return 0;
+}
+
+static int s3c24xx_spi_resume(struct platform_device *pdev)
+{
+	struct s3c24xx_spi *hw = platform_get_drvdata(dev);
+
+	clk_enable(hw->clk);
+	return 0;
+}
+
+#else
+#define s3c24xx_spi_suspend NULL
+#define s3c24xx_spi_resume  NULL
+#endif
+
+static struct platform_driver s3c24xx_spidrv = {
+	.probe		= s3c24xx_spi_probe,
+	.remove		= s3c24xx_spi_remove,
+	.suspend	= s3c24xx_spi_suspend,
+	.resume		= s3c24xx_spi_resume,
+	.driver		= {
+		.name	= "s3c2410-spi",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init s3c24xx_spi_init(void)
+{
+        return platform_driver_register(&s3c24xx_spidrv);
+}
+
+static void __exit s3c24xx_spi_exit(void)
+{
+        platform_driver_unregister(&s3c24xx_spidrv);
+}
+
+module_init(s3c24xx_spi_init);
+module_exit(s3c24xx_spi_exit);
+
+MODULE_DESCRIPTION("S3C24XX SPI Driver");
+MODULE_AUTHOR("Ben Dooks, <[e-mail]>");
+MODULE_LICENSE("GPL");

include/asm-arm/arch-s3c2410/spi.h

···
+/* linux/include/asm-arm/arch-s3c2410/spi.h
+ *
+ * Copyright (c) 2006 Simtec Electronics
+ *	Ben Dooks <[e-mail]>
+ *
+ * S3C2410 - SPI Controller platform_device info
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#ifndef __ASM_ARCH_SPI_H
+#define __ASM_ARCH_SPI_H __FILE__
+
+struct s3c2410_spi_info;
+struct spi_board_info;
+
+struct s3c2410_spi_info {
+	unsigned long		 pin_cs;	/* simple gpio cs */
+
+	unsigned long		 board_size;
+	struct spi_board_info	*board_info;
+
+	void (*set_cs)(struct s3c2410_spi_info *spi, int cs, int pol);
+};
+
+
+#endif /* __ASM_ARCH_SPI_H */