diff options
Diffstat (limited to 'package/kernel/spi-gpio-custom/src/spi-gpio-custom.c')
| -rw-r--r-- | package/kernel/spi-gpio-custom/src/spi-gpio-custom.c | 365 |
1 files changed, 365 insertions, 0 deletions
diff --git a/package/kernel/spi-gpio-custom/src/spi-gpio-custom.c b/package/kernel/spi-gpio-custom/src/spi-gpio-custom.c new file mode 100644 index 0000000000..a4f93c67c2 --- /dev/null +++ b/package/kernel/spi-gpio-custom/src/spi-gpio-custom.c @@ -0,0 +1,365 @@ +/* + * 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); |