[PATCH] S3C24XX: GPIO based SPI driver

SPI driver for SPI by GPIO on the Samsung S3C24XX series of SoC processors.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Cc: Greg KH <greg@kroah.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/spi/Kconfig

@@ -95,6 +95,14 @@ config SPI_PXA2XX
 	  The driver can be configured to use any SSP port and additional
 	  documentation can be found a Documentation/spi/pxa2xx.
 
+config SPI_S3C24XX_GPIO
+	tristate "Samsung S3C24XX series SPI by GPIO"
+	depends on SPI_MASTER && ARCH_S3C2410 && SPI_BITBANG && EXPERIMENTAL
+	help
+	  SPI driver for Samsung S3C24XX series ARM SoCs using
+	  GPIO lines to provide the SPI bus. This can be used where
+	  the inbuilt hardware cannot provide the transfer mode, or
+	  where the board is using non hardware connected pins.
 #
 # Add new SPI master controllers in alphabetical order above this line
 #

drivers/spi/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_SPI_BITBANG)		+= spi_bitbang.o
 obj-$(CONFIG_SPI_BUTTERFLY)		+= spi_butterfly.o
 obj-$(CONFIG_SPI_PXA2XX)		+= pxa2xx_spi.o
 obj-$(CONFIG_SPI_MPC83xx)		+= spi_mpc83xx.o
+obj-$(CONFIG_SPI_S3C24XX_GPIO)		+= spi_s3c24xx_gpio.o
 # 	... add above this line ...
 
 # SPI protocol drivers (device/link on bus)

drivers/spi/spi_butterfly.c

@@ -321,6 +321,7 @@ static void butterfly_attach(struct parport *p)
 	 * (firmware resets at45, acts as spi slave) or neither (we ignore
 	 * both, AVR uses AT45).  Here we expect firmware for the first option.
 	 */
+
 	pp->info[0].max_speed_hz = 15 * 1000 * 1000;
 	strcpy(pp->info[0].modalias, "mtd_dataflash");
 	pp->info[0].platform_data = &flash;

drivers/spi/spi_s3c24xx_gpio.c

+/* linux/drivers/spi/spi_s3c24xx_gpio.c
+ *
+ * Copyright (c) 2006 Ben Dooks
+ * Copyright (c) 2006 Simtec Electronics
+ *
+ * S3C24XX GPIO based SPI driver
+ *
+ * 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.
+ *
+*/
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/platform_device.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+#include <asm/arch/regs-gpio.h>
+#include <asm/arch/spi-gpio.h>
+#include <asm/arch/hardware.h>
+
+struct s3c2410_spigpio {
+	struct spi_bitbang		 bitbang;
+
+	struct s3c2410_spigpio_info	*info;
+	struct platform_device		*dev;
+};
+
+static inline struct s3c2410_spigpio *spidev_to_sg(struct spi_device *spi)
+{
+	return spi->controller_data;
+}
+
+static inline void setsck(struct spi_device *dev, int on)
+{
+	struct s3c2410_spigpio *sg = spidev_to_sg(dev);
+	s3c2410_gpio_setpin(sg->info->pin_clk, on ? 1 : 0);
+}
+
+static inline void setmosi(struct spi_device *dev, int on)
+{
+	struct s3c2410_spigpio *sg = spidev_to_sg(dev);
+	s3c2410_gpio_setpin(sg->info->pin_mosi, on ? 1 : 0);
+}
+
+static inline u32 getmiso(struct spi_device *dev)
+{
+	struct s3c2410_spigpio *sg = spidev_to_sg(dev);
+	return s3c2410_gpio_getpin(sg->info->pin_miso) ? 1 : 0;
+}
+
+#define spidelay(x) ndelay(x)
+
+#define	EXPAND_BITBANG_TXRX
+#include <linux/spi/spi_bitbang.h>
+
+
+static u32 s3c2410_spigpio_txrx_mode0(struct spi_device *spi,
+				      unsigned nsecs, u32 word, u8 bits)
+{
+	return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
+}
+
+static u32 s3c2410_spigpio_txrx_mode1(struct spi_device *spi,
+				      unsigned nsecs, u32 word, u8 bits)
+{
+	return bitbang_txrx_be_cpha1(spi, nsecs, 0, word, bits);
+}
+
+static void s3c2410_spigpio_chipselect(struct spi_device *dev, int value)
+{
+	struct s3c2410_spigpio *sg = spidev_to_sg(dev);
+
+	if (sg->info && sg->info->chip_select)
+		(sg->info->chip_select)(sg->info, value);
+}
+
+static int s3c2410_spigpio_probe(struct platform_device *dev)
+{
+	struct spi_master	*master;
+	struct s3c2410_spigpio  *sp;
+	int ret;
+	int i;
+
+	master = spi_alloc_master(&dev->dev, sizeof(struct s3c2410_spigpio));
+	if (master == NULL) {
+		dev_err(&dev->dev, "failed to allocate spi master\n");
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	sp = spi_master_get_devdata(master);
+
+	platform_set_drvdata(dev, sp);
+
+	/* copy in the plkatform data */
+	sp->info = dev->dev.platform_data;
+
+	/* setup spi bitbang adaptor */
+	sp->bitbang.master = spi_master_get(master);
+	sp->bitbang.chipselect = s3c2410_spigpio_chipselect;
+
+	sp->bitbang.txrx_word[SPI_MODE_0] = s3c2410_spigpio_txrx_mode0;
+	sp->bitbang.txrx_word[SPI_MODE_1] = s3c2410_spigpio_txrx_mode1;
+
+	/* set state of spi pins */
+	s3c2410_gpio_setpin(sp->info->pin_clk, 0);
+	s3c2410_gpio_setpin(sp->info->pin_mosi, 0);
+
+	s3c2410_gpio_cfgpin(sp->info->pin_clk, S3C2410_GPIO_OUTPUT);
+	s3c2410_gpio_cfgpin(sp->info->pin_mosi, S3C2410_GPIO_OUTPUT);
+	s3c2410_gpio_cfgpin(sp->info->pin_miso, S3C2410_GPIO_INPUT);
+
+	ret = spi_bitbang_start(&sp->bitbang);
+	if (ret)
+		goto err_no_bitbang;
+
+	/* register the chips to go with the board */
+
+	for (i = 0; i < sp->info->board_size; i++) {
+		dev_info(&dev->dev, "registering %p: %s\n",
+			 &sp->info->board_info[i],
+			 sp->info->board_info[i].modalias);
+
+		sp->info->board_info[i].controller_data = sp;
+		spi_new_device(master, sp->info->board_info + i);
+	}
+
+	return 0;
+
+ err_no_bitbang:
+	spi_master_put(sp->bitbang.master);
+ err:
+	return ret;
+
+}
+
+static int s3c2410_spigpio_remove(struct platform_device *dev)
+{
+	struct s3c2410_spigpio *sp = platform_get_drvdata(dev);
+
+	spi_bitbang_stop(&sp->bitbang);
+	spi_master_put(sp->bitbang.master);
+
+	return 0;
+}
+
+/* all gpio should be held over suspend/resume, so we should
+ * not need to deal with this
+*/
+
+#define s3c2410_spigpio_suspend NULL
+#define s3c2410_spigpio_resume NULL
+
+
+static struct platform_driver s3c2410_spigpio_drv = {
+	.probe		= s3c2410_spigpio_probe,
+        .remove		= s3c2410_spigpio_remove,
+        .suspend	= s3c2410_spigpio_suspend,
+        .resume		= s3c2410_spigpio_resume,
+        .driver		= {
+		.name	= "s3c24xx-spi-gpio",
+		.owner	= THIS_MODULE,
+        },
+};
+
+static int __init s3c2410_spigpio_init(void)
+{
+        return platform_driver_register(&s3c2410_spigpio_drv);
+}
+
+static void __exit s3c2410_spigpio_exit(void)
+{
+        platform_driver_unregister(&s3c2410_spigpio_drv);
+}
+
+module_init(s3c2410_spigpio_init);
+module_exit(s3c2410_spigpio_exit);
+
+MODULE_DESCRIPTION("S3C24XX SPI Driver");
+MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
+MODULE_LICENSE("GPL");

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

+/* linux/include/asm-arm/arch-s3c2410/spi.h
+ *
+ * Copyright (c) 2006 Simtec Electronics
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C2410 - SPI Controller platfrom_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_SPIGPIO_H
+#define __ASM_ARCH_SPIGPIO_H __FILE__
+
+struct s3c2410_spigpio_info;
+struct spi_board_info;
+
+struct s3c2410_spigpio_info {
+	unsigned long		 pin_clk;
+	unsigned long		 pin_mosi;
+	unsigned long		 pin_miso;
+
+	unsigned long		 board_size;
+	struct spi_board_info	*board_info;
+
+	void (*chip_select)(struct s3c2410_spigpio_info *spi, int cs);
+};
+
+
+#endif /* __ASM_ARCH_SPIGPIO_H */