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