--- /dev/null
+/*
+ * Custom GPIO-based SPI driver
+ *
+ * Copyright (C) 2013 Marco Burato <zmaster.adsl@gmail.com>
+ *
+ * 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.
+ *
+ * Based on i2c-gpio-custom by:
+ * Copyright (C) 2007-2008 Gabor Juhos <juhosg@openwrt.org>
+ * ---------------------------------------------------------------------------
+ *
+ * The behaviour of this driver can be altered by setting some parameters
+ * from the insmod command line.
+ *
+ * The following parameters are adjustable:
+ *
+ * bus0 These four arguments can be arrays of
+ * bus1 1-8 unsigned integers as follows:
+ * bus2
+ * bus3 <id>,<sck>,<mosi>,<miso>,<mode1>,<maxfreq1>,<cs1>,...
+ *
+ * where:
+ *
+ * <id> ID to used as device_id for the corresponding bus (required)
+ * <sck> GPIO pin ID to be used for bus SCK (required)
+ * <mosi> GPIO pin ID to be used for bus MOSI (required*)
+ * <miso> GPIO pin ID to be used for bus MISO (required*)
+ * <modeX> Mode configuration for slave X in the bus (required)
+ * (see /include/linux/spi/spi.h)
+ * <maxfreqX> Maximum clock frequency in Hz for slave X in the bus (required)
+ * <csX> GPIO pin ID to be used for slave X CS (required**)
+ *
+ * Notes:
+ * * If a signal is not used (for example there is no MISO) you need
+ * to set the GPIO pin ID for that signal to an invalid value.
+ * ** If you only have 1 slave in the bus with no CS, you can omit the
+ * <cs1> param or set it to an invalid GPIO id to disable it. When
+ * you have 2 or more slaves, they must all have a valid CS.
+ *
+ * If this driver is built into the kernel, you can use the following kernel
+ * command line parameters, with the same values as the corresponding module
+ * parameters listed above:
+ *
+ * spi-gpio-custom.bus0
+ * spi-gpio-custom.bus1
+ * spi-gpio-custom.bus2
+ * spi-gpio-custom.bus3
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+
+#include <linux/gpio.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_gpio.h>
+
+#define DRV_NAME "spi-gpio-custom"
+#define DRV_DESC "Custom GPIO-based SPI driver"
+#define DRV_VERSION "0.1"
+
+#define PFX DRV_NAME ": "
+
+#define BUS_PARAM_ID 0
+#define BUS_PARAM_SCK 1
+#define BUS_PARAM_MOSI 2
+#define BUS_PARAM_MISO 3
+#define BUS_PARAM_MODE1 4
+#define BUS_PARAM_MAXFREQ1 5
+#define BUS_PARAM_CS1 6
+
+#define BUS_SLAVE_COUNT_MAX 8
+#define BUS_PARAM_REQUIRED 6
+#define BUS_PARAM_PER_SLAVE 3
+#define BUS_PARAM_COUNT (4+BUS_PARAM_PER_SLAVE*BUS_SLAVE_COUNT_MAX)
+#define BUS_COUNT_MAX 4
+
+static unsigned int bus0[BUS_PARAM_COUNT] __initdata;
+static unsigned int bus1[BUS_PARAM_COUNT] __initdata;
+static unsigned int bus2[BUS_PARAM_COUNT] __initdata;
+static unsigned int bus3[BUS_PARAM_COUNT] __initdata;
+
+static unsigned int bus_nump[BUS_COUNT_MAX] __initdata;
+
+#define BUS_PARM_DESC \
+ " config -> id,sck,mosi,miso,mode1,maxfreq1[,cs1,mode2,maxfreq2,cs2,...]"
+
+module_param_array(bus0, uint, &bus_nump[0], 0);
+MODULE_PARM_DESC(bus0, "bus0" BUS_PARM_DESC);
+module_param_array(bus1, uint, &bus_nump[1], 0);
+MODULE_PARM_DESC(bus1, "bus1" BUS_PARM_DESC);
+module_param_array(bus2, uint, &bus_nump[2], 0);
+MODULE_PARM_DESC(bus2, "bus2" BUS_PARM_DESC);
+module_param_array(bus3, uint, &bus_nump[3], 0);
+MODULE_PARM_DESC(bus3, "bus3" BUS_PARM_DESC);
+
+static struct platform_device *devices[BUS_COUNT_MAX];
+static unsigned int nr_devices;
+
+static void spi_gpio_custom_cleanup(void)
+{
+ int i;
+
+ for (i = 0; i < nr_devices; i++)
+ if (devices[i])
+ platform_device_unregister(devices[i]);
+}
+
+static int spi_gpio_custom_get_slave_mode(unsigned int id,
+ unsigned int *params,
+ int slave_index)
+{
+ int param_index;
+
+ param_index = BUS_PARAM_MODE1+slave_index*BUS_PARAM_PER_SLAVE;
+ if (param_index >= bus_nump[id])
+ return -1;
+
+ return params[param_index];
+}
+static int spi_gpio_custom_get_slave_maxfreq(unsigned int id,
+ unsigned int *params,
+ int slave_index)
+{
+ int param_index;
+
+ param_index = BUS_PARAM_MAXFREQ1+slave_index*BUS_PARAM_PER_SLAVE;
+ if (param_index >= bus_nump[id])
+ return -1;
+
+ return params[param_index];
+}
+static int spi_gpio_custom_get_slave_cs(unsigned int id,
+ unsigned int *params,
+ int slave_index)
+{
+ int param_index;
+
+ param_index = BUS_PARAM_CS1+slave_index*BUS_PARAM_PER_SLAVE;
+ if (param_index >= bus_nump[id])
+ return -1;
+ if (!gpio_is_valid(params[param_index]))
+ return -1;
+
+ return params[param_index];
+}
+
+static int spi_gpio_custom_check_params(unsigned int id, unsigned int *params)
+{
+ int i;
+ struct spi_master *master;
+
+ if (bus_nump[id] < BUS_PARAM_REQUIRED) {
+ printk(KERN_ERR PFX "not enough values for parameter bus%d\n",
+ id);
+ return -EINVAL;
+ }
+
+ if (bus_nump[id] > (1+BUS_PARAM_CS1)) {
+ /* more than 1 device: check CS GPIOs */
+ for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
+ /* no more slaves? */
+ if (spi_gpio_custom_get_slave_mode(id, params, i) < 0)
+ break;
+
+ if (spi_gpio_custom_get_slave_cs(id, params, i) < 0) {
+ printk(KERN_ERR PFX "invalid/missing CS gpio for slave %d on bus %d\n",
+ i, params[BUS_PARAM_ID]);
+ return -EINVAL;
+ }
+ }
+ }
+
+ if (!gpio_is_valid(params[BUS_PARAM_SCK])) {
+ printk(KERN_ERR PFX "invalid SCK gpio for bus %d\n",
+ params[BUS_PARAM_ID]);
+ return -EINVAL;
+ }
+
+ master = spi_busnum_to_master(params[BUS_PARAM_ID]);
+ if (master) {
+ spi_master_put(master);
+ printk(KERN_ERR PFX "bus %d already exists\n",
+ params[BUS_PARAM_ID]);
+ return -EEXIST;
+ }
+
+ return 0;
+}
+
+static int __init spi_gpio_custom_add_one(unsigned int id, unsigned int *params)
+{
+ struct platform_device *pdev;
+ struct spi_gpio_platform_data pdata;
+ int i;
+ int num_cs;
+ int err;
+ struct spi_master *master;
+ struct spi_device *slave;
+ struct spi_board_info slave_info;
+ int mode, maxfreq, cs;
+
+
+ if (!bus_nump[id])
+ return 0;
+
+ err = spi_gpio_custom_check_params(id, params);
+ if (err)
+ goto err;
+
+ /* Create BUS device node */
+
+ pdev = platform_device_alloc("spi_gpio", params[BUS_PARAM_ID]);
+ if (!pdev) {
+ err = -ENOMEM;
+ goto err;
+ }
+
+ num_cs = 0;
+ for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
+ /* no more slaves? */
+ if (spi_gpio_custom_get_slave_mode(id, params, i) < 0)
+ break;
+
+ if (spi_gpio_custom_get_slave_cs(id, params, i) >= 0)
+ num_cs++;
+ }
+ if (num_cs == 0) {
+ /*
+ * Even if no CS is used, spi modules expect
+ * at least 1 (unused)
+ */
+ num_cs = 1;
+ }
+
+ pdata.sck = params[BUS_PARAM_SCK];
+ pdata.mosi = gpio_is_valid(params[BUS_PARAM_MOSI])
+ ? params[BUS_PARAM_MOSI]
+ : SPI_GPIO_NO_MOSI;
+ pdata.miso = gpio_is_valid(params[BUS_PARAM_MISO])
+ ? params[BUS_PARAM_MISO]
+ : SPI_GPIO_NO_MISO;
+ pdata.num_chipselect = num_cs;
+
+ err = platform_device_add_data(pdev, &pdata, sizeof(pdata));
+ if (err) {
+ platform_device_put(pdev);
+ goto err;
+ }
+
+ err = platform_device_add(pdev);
+ if (err) {
+ printk(KERN_ERR PFX "platform_device_add failed with return code %d\n",
+ err);
+ platform_device_put(pdev);
+ goto err;
+ }
+
+ /* Register SLAVE devices */
+
+ for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
+ mode = spi_gpio_custom_get_slave_mode(id, params, i);
+ maxfreq = spi_gpio_custom_get_slave_maxfreq(id, params, i);
+ cs = spi_gpio_custom_get_slave_cs(id, params, i);
+
+ /* no more slaves? */
+ if (mode < 0)
+ break;
+
+ memset(&slave_info, 0, sizeof(slave_info));
+ strcpy(slave_info.modalias, "spidev");
+ slave_info.controller_data = (void *)((cs >= 0)
+ ? cs
+ : SPI_GPIO_NO_CHIPSELECT);
+ slave_info.max_speed_hz = maxfreq;
+ slave_info.bus_num = params[BUS_PARAM_ID];
+ slave_info.chip_select = i;
+ slave_info.mode = mode;
+
+ master = spi_busnum_to_master(params[BUS_PARAM_ID]);
+ if (!master) {
+ printk(KERN_ERR PFX "unable to get master for bus %d\n",
+ params[BUS_PARAM_ID]);
+ err = -EINVAL;
+ goto err_unregister;
+ }
+ slave = spi_new_device(master, &slave_info);
+ spi_master_put(master);
+ if (!slave) {
+ printk(KERN_ERR PFX "unable to create slave %d for bus %d\n",
+ i, params[BUS_PARAM_ID]);
+ /* Will most likely fail due to unsupported mode bits */
+ err = -EINVAL;
+ goto err_unregister;
+ }
+ }
+
+ devices[nr_devices++] = pdev;
+
+ return 0;
+
+err_unregister:
+ platform_device_unregister(pdev);
+err:
+ return err;
+}
+
+static int __init spi_gpio_custom_probe(void)
+{
+ int err;
+
+ printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");
+
+ err = spi_gpio_custom_add_one(0, bus0);
+ if (err)
+ goto err;
+
+ err = spi_gpio_custom_add_one(1, bus1);
+ if (err)
+ goto err;
+
+ err = spi_gpio_custom_add_one(2, bus2);
+ if (err)
+ goto err;
+
+ err = spi_gpio_custom_add_one(3, bus3);
+ if (err)
+ goto err;
+
+ if (!nr_devices) {
+ printk(KERN_ERR PFX "no bus parameter(s) specified\n");
+ err = -ENODEV;
+ goto err;
+ }
+
+ return 0;
+
+err:
+ spi_gpio_custom_cleanup();
+ return err;
+}
+
+#ifdef MODULE
+static int __init spi_gpio_custom_init(void)
+{
+ return spi_gpio_custom_probe();
+}
+module_init(spi_gpio_custom_init);
+
+static void __exit spi_gpio_custom_exit(void)
+{
+ spi_gpio_custom_cleanup();
+}
+module_exit(spi_gpio_custom_exit);
+#else
+subsys_initcall(spi_gpio_custom_probe);
+#endif /* MODULE*/
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Marco Burato <zmaster.adsl@gmail.com>");
+MODULE_DESCRIPTION(DRV_DESC);
+MODULE_VERSION(DRV_VERSION);
projects / openwrt / openwrt.git / blobdiff