Add dynamic MMC-over-SPI-GPIO driver

Index: linux-next/drivers/mmc/host/mmc_over_spigpio.c
===================================================================
@@ -0,0 +1,339 @@
+/*
+ * Driver for driving an MMC card over a bitbanging GPIO SPI bus.
+ *
+ * Copyright 2008 Michael Buesch <[email protected]>
+ *
+ * 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);