path: root/package/mmc_over_gpio/src/mmc_over_spigpio.c

/*
 * Driver for driving an MMC card over a bitbanging GPIO SPI bus.
 *
 * Copyright 2008 Michael Buesch <mb@bu3sch.de>
 *
 * Licensed under the GNU/GPL. See COPYING for details.
 */

#include <linux/platform_device.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/spi/spi_gpio.h>


/* This is the maximum speed in Hz */
#define GPIOMMC_MAXSPEED	5000000 /* Hz */


#define DRIVER_NAME		"spi-gpio-mmc"
#define PFX			DRIVER_NAME ": "


#define GPIOMMC_MAX_NAMELEN		15
#define GPIOMMC_MAX_NAMELEN_STR		__stringify(GPIOMMC_MAX_NAMELEN)

struct gpiommc_pins {
	unsigned int gpio_di;	/* Card DI pin */
	unsigned int gpio_do;	/* Card DO pin */
	unsigned int gpio_clk;	/* Card CLK pin */
	unsigned int gpio_cs;	/* Card CS pin */
};

struct gpiommc_device {
	char name[GPIOMMC_MAX_NAMELEN + 1];
	struct platform_device *pdev;
	struct platform_device *spi_pdev;
	struct gpiommc_pins pins;
	u8 mode; /* SPI_MODE_X */
	struct spi_board_info boardinfo;

	struct list_head list;
};


static LIST_HEAD(gpiommc_devices_list);
static DEFINE_MUTEX(gpiommc_mutex);


MODULE_DESCRIPTION("SPI-GPIO based MMC driver");
MODULE_AUTHOR("Michael Buesch");
MODULE_LICENSE("GPL");


static int gpiommc_boardinfo_setup(struct spi_board_info *bi,
				   struct spi_master *master,
				   void *data)
{
	struct gpiommc_device *d = data;

	/* Bind the SPI master to the MMC-SPI host driver. */
	strlcpy(bi->modalias, "mmc_spi", sizeof(bi->modalias));

	bi->max_speed_hz = GPIOMMC_MAXSPEED;
	bi->bus_num = master->bus_num;
	bi->mode = d->mode;

	return 0;
}

static int gpiommc_probe(struct platform_device *pdev)
{
	static int instance;
	struct gpiommc_device *d = platform_get_drvdata(pdev);
	struct spi_gpio_platform_data pdata;
	int err = -ENOMEM;

	d->spi_pdev = platform_device_alloc("spi-gpio", instance++);
	if (!d->spi_pdev)
		goto out;

	memset(&pdata, 0, sizeof(pdata));
	pdata.pin_clk = d->pins.gpio_clk;
	pdata.pin_miso = d->pins.gpio_do;
	pdata.pin_mosi = d->pins.gpio_di;
	pdata.pin_cs = d->pins.gpio_cs;
	pdata.cs_activelow = 1;
	pdata.no_spi_delay = 1;
	pdata.boardinfo_setup = gpiommc_boardinfo_setup;
	pdata.boardinfo_setup_data = d;

	err = platform_device_add_data(d->spi_pdev, &pdata, sizeof(pdata));
	if (err)
		goto err_free_pdev;
	err = platform_device_register(d->spi_pdev);
	if (err)
		goto err_free_pdata;

	printk(KERN_INFO PFX "MMC-Card \"%s\" "
	       "attached to GPIO pins %u,%u,%u,%u\n",
	       d->name, d->pins.gpio_di, d->pins.gpio_do,
	       d->pins.gpio_clk, d->pins.gpio_cs);
out:
	return err;

err_free_pdata:
	kfree(d->spi_pdev->dev.platform_data);
	d->spi_pdev->dev.platform_data = NULL;
err_free_pdev:
	platform_device_put(d->spi_pdev);
	return err;
}

static int gpiommc_remove(struct platform_device *pdev)
{
	struct gpiommc_device *d = platform_get_drvdata(pdev);

	platform_device_unregister(d->spi_pdev);
	printk(KERN_INFO PFX "MMC-Card \"%s\" removed\n", d->name);

	return 0;
}

static void gpiommc_free(struct gpiommc_device *d)
{
	kfree(d);
}

static struct gpiommc_device * gpiommc_alloc(struct platform_device *pdev,
					     const char *name,
					     const struct gpiommc_pins *pins,
					     u8 mode)
{
	struct gpiommc_device *d;

	d = kmalloc(sizeof(*d), GFP_KERNEL);
	if (!d)
		return NULL;

	strcpy(d->name, name);
	memcpy(&d->pins, pins, sizeof(d->pins));
	d->mode = mode;
	INIT_LIST_HEAD(&d->list);

	return d;
}

/* List must be locked. */
static struct gpiommc_device * gpiommc_find_device(const char *name)
{
	struct gpiommc_device *d;

	list_for_each_entry(d, &gpiommc_devices_list, list) {
		if (strcmp(d->name, name) == 0)
			return d;
	}

	return NULL;
}

static void gpiommc_do_destroy_device(struct gpiommc_device *d)
{
	list_del(&d->list);
	platform_device_unregister(d->pdev);
	gpiommc_free(d);
}

static int gpiommc_destroy_device(const char *name)
{
	struct gpiommc_device *d;
	int err = -ENODEV;

	mutex_lock(&gpiommc_mutex);
	d = gpiommc_find_device(name);
	if (!d)
		goto out_unlock;
	gpiommc_do_destroy_device(d);
	err = 0;
out_unlock:
	mutex_unlock(&gpiommc_mutex);

	return err;
}

static int gpiommc_create_device(const char *name,
				 const struct gpiommc_pins *pins,
				 u8 mode)
{
	static int instance;
	struct platform_device *pdev;
	struct gpiommc_device *d;
	int err;

	mutex_lock(&gpiommc_mutex);
	err = -EEXIST;
	if (gpiommc_find_device(name))
		goto out_unlock;
	err = -ENOMEM;
	pdev = platform_device_alloc(DRIVER_NAME, instance++);
	if (!pdev)
		goto out_unlock;
	d = gpiommc_alloc(pdev, name, pins, mode);
	if (!d)
		goto err_free_pdev;
	platform_set_drvdata(pdev, d);
	d->pdev = pdev;
	err = platform_device_register(pdev);
	if (err)
		goto err_free_mdev;
	list_add(&d->list, &gpiommc_devices_list);

	err = 0;
out_unlock:
	mutex_unlock(&gpiommc_mutex);

	return err;

err_free_mdev:
	gpiommc_free(d);
err_free_pdev:
	platform_device_put(pdev);
	goto out_unlock;
}

static ssize_t gpiommc_add_show(struct device_driver *drv,
				char *buf)
{
	return snprintf(buf, PAGE_SIZE, "NAME  DI_pin,DO_pin,CLK_pin,CS_pin  [MODE]\n");
}

static ssize_t gpiommc_add_store(struct device_driver *drv,
				 const char *buf, size_t count)
{
	int res, err;
	char name[GPIOMMC_MAX_NAMELEN + 1];
	struct gpiommc_pins pins;
	unsigned int mode;

	res = sscanf(buf, "%" GPIOMMC_MAX_NAMELEN_STR "s %u,%u,%u,%u %u",
		     name, &pins.gpio_di, &pins.gpio_do,
		     &pins.gpio_clk, &pins.gpio_cs, &mode);
	if (res == 5)
		mode = 0;
	else if (res != 6)
		return -EINVAL;
	switch (mode) {
	case 0:
		mode = SPI_MODE_0;
		break;
	case 1:
		mode = SPI_MODE_1;
		break;
	case 2:
		mode = SPI_MODE_2;
		break;
	case 3:
		mode = SPI_MODE_3;
		break;
	default:
		return -EINVAL;
	}
	err = gpiommc_create_device(name, &pins, mode);

	return err ? err : count;
}

static ssize_t gpiommc_remove_show(struct device_driver *drv,
				   char *buf)
{
	return snprintf(buf, PAGE_SIZE, "write device-name to remove the device\n");
}

static ssize_t gpiommc_remove_store(struct device_driver *drv,
				    const char *buf, size_t count)
{
	int err;

	err = gpiommc_destroy_device(buf);

	return err ? err : count;
}

static DRIVER_ATTR(add, 0600,
		   gpiommc_add_show, gpiommc_add_store);
static DRIVER_ATTR(remove, 0600,
		   gpiommc_remove_show, gpiommc_remove_store);

static struct platform_driver gpiommc_plat_driver = {
	.probe	= gpiommc_probe,
	.remove	= gpiommc_remove,
	.driver	= {
		.name	= DRIVER_NAME,
		.owner	= THIS_MODULE,
	},
};

static int __init gpiommc_modinit(void)
{
	int err;

	err = platform_driver_register(&gpiommc_plat_driver);
	if (err)
		return err;
	err = driver_create_file(&gpiommc_plat_driver.driver,
				 &driver_attr_add);
	if (err)
		goto err_drv_unreg;
	err = driver_create_file(&gpiommc_plat_driver.driver,
				 &driver_attr_remove);
	if (err)
		goto err_remove_add;

	return 0;

err_remove_add:
	driver_remove_file(&gpiommc_plat_driver.driver,
			   &driver_attr_add);
err_drv_unreg:
	platform_driver_unregister(&gpiommc_plat_driver);
	return err;
}
module_init(gpiommc_modinit);

static void __exit gpiommc_modexit(void)
{
	struct gpiommc_device *d, *tmp;

	driver_remove_file(&gpiommc_plat_driver.driver,
			   &driver_attr_remove);
	driver_remove_file(&gpiommc_plat_driver.driver,
			   &driver_attr_add);

	mutex_lock(&gpiommc_mutex);
	list_for_each_entry_safe(d, tmp, &gpiommc_devices_list, list)
		gpiommc_do_destroy_device(d);
	mutex_unlock(&gpiommc_mutex);

	platform_driver_unregister(&gpiommc_plat_driver);
}
module_exit(gpiommc_modexit);