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/*
* 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);
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