package/kernel/spi-gpio-custom/src/spi-gpio-custom.c

   1 /*
   2  *  Custom GPIO-based SPI driver
   3  *
   4  *  Copyright (C) 2013 Marco Burato <zmaster.adsl@gmail.com>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2 as
   8  *  published by the Free Software Foundation.
   9  *
  10  *  Based on i2c-gpio-custom by:
  11  *  Copyright (C) 2007-2008 Gabor Juhos <juhosg@openwrt.org>
  12  * ---------------------------------------------------------------------------
  13  *
  14  *  The behaviour of this driver can be altered by setting some parameters
  15  *  from the insmod command line.
  16  *
  17  *  The following parameters are adjustable:
  18  *
  19  *      bus0    These four arguments can be arrays of
  20  *      bus1    1-8 unsigned integers as follows:
  21  *      bus2
  22  *      bus3    <id>,<sck>,<mosi>,<miso>,<mode1>,<maxfreq1>,<cs1>,...
  23  *
  24  *  where:
  25  *
  26  *  <id>        ID to used as device_id for the corresponding bus (required)
  27  *  <sck>       GPIO pin ID to be used for bus SCK (required)
  28  *  <mosi>      GPIO pin ID to be used for bus MOSI (required*)
  29  *  <miso>      GPIO pin ID to be used for bus MISO (required*)
  30  *  <modeX>     Mode configuration for slave X in the bus (required)
  31  *              (see /include/linux/spi/spi.h)
  32  *  <maxfreqX>  Maximum clock frequency in Hz for slave X in the bus (required)
  33  *  <csX>       GPIO pin ID to be used for slave X CS (required**)
  34  *
  35  *      Notes:
  36  *      *       If a signal is not used (for example there is no MISO) you need
  37  *              to set the GPIO pin ID for that signal to an invalid value.
  38  *      **      If you only have 1 slave in the bus with no CS, you can omit the
  39  *              <cs1> param or set it to an invalid GPIO id to disable it. When
  40  *              you have 2 or more slaves, they must all have a valid CS.
  41  *
  42  *  If this driver is built into the kernel, you can use the following kernel
  43  *  command line parameters, with the same values as the corresponding module
  44  *  parameters listed above:
  45  *
  46  *      spi-gpio-custom.bus0
  47  *      spi-gpio-custom.bus1
  48  *      spi-gpio-custom.bus2
  49  *      spi-gpio-custom.bus3
  50  */
  51
  52 #include <linux/kernel.h>
  53 #include <linux/module.h>
  54 #include <linux/init.h>
  55 #include <linux/platform_device.h>
  56
  57 #include <linux/gpio.h>
  58 #include <linux/spi/spi.h>
  59 #include <linux/spi/spi_gpio.h>
  60
  61 #define DRV_NAME        "spi-gpio-custom"
  62 #define DRV_DESC        "Custom GPIO-based SPI driver"
  63 #define DRV_VERSION     "0.1"
  64
  65 #define PFX             DRV_NAME ": "
  66
  67 #define BUS_PARAM_ID            0
  68 #define BUS_PARAM_SCK           1
  69 #define BUS_PARAM_MOSI          2
  70 #define BUS_PARAM_MISO          3
  71 #define BUS_PARAM_MODE1         4
  72 #define BUS_PARAM_MAXFREQ1      5
  73 #define BUS_PARAM_CS1           6
  74
  75 #define BUS_SLAVE_COUNT_MAX     8
  76 #define BUS_PARAM_REQUIRED      6
  77 #define BUS_PARAM_PER_SLAVE     3
  78 #define BUS_PARAM_COUNT         (4+BUS_PARAM_PER_SLAVE*BUS_SLAVE_COUNT_MAX)
  79 #define BUS_COUNT_MAX           4
  80
  81 static unsigned int bus0[BUS_PARAM_COUNT] __initdata;
  82 static unsigned int bus1[BUS_PARAM_COUNT] __initdata;
  83 static unsigned int bus2[BUS_PARAM_COUNT] __initdata;
  84 static unsigned int bus3[BUS_PARAM_COUNT] __initdata;
  85
  86 static unsigned int bus_nump[BUS_COUNT_MAX] __initdata;
  87
  88 #define BUS_PARM_DESC \
  89         " config -> id,sck,mosi,miso,mode1,maxfreq1[,cs1,mode2,maxfreq2,cs2,...]"
  90
  91 module_param_array(bus0, uint, &bus_nump[0], 0);
  92 MODULE_PARM_DESC(bus0, "bus0" BUS_PARM_DESC);
  93 module_param_array(bus1, uint, &bus_nump[1], 0);
  94 MODULE_PARM_DESC(bus1, "bus1" BUS_PARM_DESC);
  95 module_param_array(bus2, uint, &bus_nump[2], 0);
  96 MODULE_PARM_DESC(bus2, "bus2" BUS_PARM_DESC);
  97 module_param_array(bus3, uint, &bus_nump[3], 0);
  98 MODULE_PARM_DESC(bus3, "bus3" BUS_PARM_DESC);
  99
 100 static struct platform_device *devices[BUS_COUNT_MAX];
 101 static unsigned int nr_devices;
 102
 103 static void spi_gpio_custom_cleanup(void)
 104 {
 105         int i;
 106
 107         for (i = 0; i < nr_devices; i++)
 108                 if (devices[i])
 109                         platform_device_unregister(devices[i]);
 110 }
 111
 112 static int __init spi_gpio_custom_get_slave_mode(unsigned int id,
 113                                           unsigned int *params,
 114                                           int slave_index)
 115 {
 116         int param_index;
 117
 118         param_index = BUS_PARAM_MODE1+slave_index*BUS_PARAM_PER_SLAVE;
 119         if (param_index >= bus_nump[id])
 120                 return -1;
 121
 122         return params[param_index];
 123 }
 124 static int __init spi_gpio_custom_get_slave_maxfreq(unsigned int id,
 125                                              unsigned int *params,
 126                                              int slave_index)
 127 {
 128         int param_index;
 129
 130         param_index = BUS_PARAM_MAXFREQ1+slave_index*BUS_PARAM_PER_SLAVE;
 131         if (param_index >= bus_nump[id])
 132                 return -1;
 133
 134         return params[param_index];
 135 }
 136 static int __init spi_gpio_custom_get_slave_cs(unsigned int id,
 137                                         unsigned int *params,
 138                                         int slave_index)
 139 {
 140         int param_index;
 141
 142         param_index = BUS_PARAM_CS1+slave_index*BUS_PARAM_PER_SLAVE;
 143         if (param_index >= bus_nump[id])
 144                 return -1;
 145         if (!gpio_is_valid(params[param_index]))
 146                 return -1;
 147
 148         return params[param_index];
 149 }
 150
 151 static int __init spi_gpio_custom_check_params(unsigned int id, unsigned int *params)
 152 {
 153         int i;
 154         struct spi_master *master;
 155
 156         if (bus_nump[id] < BUS_PARAM_REQUIRED) {
 157                 printk(KERN_ERR PFX "not enough values for parameter bus%d\n",
 158                        id);
 159                 return -EINVAL;
 160         }
 161
 162         if (bus_nump[id] > (1+BUS_PARAM_CS1)) {
 163                 /* more than 1 device: check CS GPIOs */
 164                 for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
 165                         /* no more slaves? */
 166                         if (spi_gpio_custom_get_slave_mode(id, params, i) < 0)
 167                                 break;
 168
 169                         if (spi_gpio_custom_get_slave_cs(id, params, i) < 0) {
 170                                 printk(KERN_ERR PFX "invalid/missing CS gpio for slave %d on bus %d\n",
 171                                        i, params[BUS_PARAM_ID]);
 172                                 return -EINVAL;
 173                         }
 174                 }
 175         }
 176
 177         if (!gpio_is_valid(params[BUS_PARAM_SCK])) {
 178                 printk(KERN_ERR PFX "invalid SCK gpio for bus %d\n",
 179                        params[BUS_PARAM_ID]);
 180                 return -EINVAL;
 181         }
 182
 183         master = spi_busnum_to_master(params[BUS_PARAM_ID]);
 184         if (master) {
 185                 spi_master_put(master);
 186                 printk(KERN_ERR PFX "bus %d already exists\n",
 187                        params[BUS_PARAM_ID]);
 188                 return -EEXIST;
 189         }
 190
 191         return 0;
 192 }
 193
 194 static int __init spi_gpio_custom_add_one(unsigned int id, unsigned int *params)
 195 {
 196         struct platform_device *pdev;
 197         struct spi_gpio_platform_data pdata;
 198         int i;
 199         int num_cs;
 200         int err;
 201         struct spi_master *master;
 202         struct spi_device *slave;
 203         struct spi_board_info slave_info;
 204         int mode, maxfreq, cs;
 205
 206
 207         if (!bus_nump[id])
 208                 return 0;
 209
 210         err = spi_gpio_custom_check_params(id, params);
 211         if (err)
 212                 goto err;
 213
 214         /* Create BUS device node */
 215
 216         pdev = platform_device_alloc("spi_gpio", params[BUS_PARAM_ID]);
 217         if (!pdev) {
 218                 err = -ENOMEM;
 219                 goto err;
 220         }
 221
 222         num_cs = 0;
 223         for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
 224                 /* no more slaves? */
 225                 if (spi_gpio_custom_get_slave_mode(id, params, i) < 0)
 226                         break;
 227
 228                 if (spi_gpio_custom_get_slave_cs(id, params, i) >= 0)
 229                         num_cs++;
 230         }
 231         if (num_cs == 0) {
 232                 /*
 233                  * Even if no CS is used, spi modules expect
 234                  * at least 1 (unused)
 235                  */
 236                 num_cs = 1;
 237         }
 238
 239         pdata.sck = params[BUS_PARAM_SCK];
 240         pdata.mosi = gpio_is_valid(params[BUS_PARAM_MOSI])
 241                 ? params[BUS_PARAM_MOSI]
 242                 : SPI_GPIO_NO_MOSI;
 243         pdata.miso = gpio_is_valid(params[BUS_PARAM_MISO])
 244                 ? params[BUS_PARAM_MISO]
 245                 : SPI_GPIO_NO_MISO;
 246         pdata.num_chipselect = num_cs;
 247
 248         err = platform_device_add_data(pdev, &pdata, sizeof(pdata));
 249         if (err) {
 250                 platform_device_put(pdev);
 251                 goto err;
 252         }
 253
 254         err = platform_device_add(pdev);
 255         if (err) {
 256                 printk(KERN_ERR PFX "platform_device_add failed with return code %d\n",
 257                        err);
 258                 platform_device_put(pdev);
 259                 goto err;
 260         }
 261
 262         /* Register SLAVE devices */
 263
 264         for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
 265                 mode = spi_gpio_custom_get_slave_mode(id, params, i);
 266                 maxfreq = spi_gpio_custom_get_slave_maxfreq(id, params, i);
 267                 cs = spi_gpio_custom_get_slave_cs(id, params, i);
 268
 269                 /* no more slaves? */
 270                 if (mode < 0)
 271                         break;
 272
 273                 memset(&slave_info, 0, sizeof(slave_info));
 274                 strcpy(slave_info.modalias, "spidev");
 275                 slave_info.controller_data = (void *)((cs >= 0)
 276                         ? cs
 277                         : SPI_GPIO_NO_CHIPSELECT);
 278                 slave_info.max_speed_hz = maxfreq;
 279                 slave_info.bus_num = params[BUS_PARAM_ID];
 280                 slave_info.chip_select = i;
 281                 slave_info.mode = mode;
 282
 283                 master = spi_busnum_to_master(params[BUS_PARAM_ID]);
 284                 if (!master) {
 285                         printk(KERN_ERR PFX "unable to get master for bus %d\n",
 286                                params[BUS_PARAM_ID]);
 287                         err = -EINVAL;
 288                         goto err_unregister;
 289                 }
 290                 slave = spi_new_device(master, &slave_info);
 291                 spi_master_put(master);
 292                 if (!slave) {
 293                         printk(KERN_ERR PFX "unable to create slave %d for bus %d\n",
 294                                i, params[BUS_PARAM_ID]);
 295                         /* Will most likely fail due to unsupported mode bits */
 296                         err = -EINVAL;
 297                         goto err_unregister;
 298                 }
 299         }
 300
 301         devices[nr_devices++] = pdev;
 302
 303         return 0;
 304
 305 err_unregister:
 306         platform_device_unregister(pdev);
 307 err:
 308         return err;
 309 }
 310
 311 static int __init spi_gpio_custom_probe(void)
 312 {
 313         int err;
 314
 315         printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");
 316
 317         err = spi_gpio_custom_add_one(0, bus0);
 318         if (err)
 319                 goto err;
 320
 321         err = spi_gpio_custom_add_one(1, bus1);
 322         if (err)
 323                 goto err;
 324
 325         err = spi_gpio_custom_add_one(2, bus2);
 326         if (err)
 327                 goto err;
 328
 329         err = spi_gpio_custom_add_one(3, bus3);
 330         if (err)
 331                 goto err;
 332
 333         if (!nr_devices) {
 334                 printk(KERN_ERR PFX "no bus parameter(s) specified\n");
 335                 err = -ENODEV;
 336                 goto err;
 337         }
 338
 339         return 0;
 340
 341 err:
 342         spi_gpio_custom_cleanup();
 343         return err;
 344 }
 345
 346 #ifdef MODULE
 347 static int __init spi_gpio_custom_init(void)
 348 {
 349         return spi_gpio_custom_probe();
 350 }
 351 module_init(spi_gpio_custom_init);
 352
 353 static void __exit spi_gpio_custom_exit(void)
 354 {
 355         spi_gpio_custom_cleanup();
 356 }
 357 module_exit(spi_gpio_custom_exit);
 358 #else
 359 subsys_initcall(spi_gpio_custom_probe);
 360 #endif /* MODULE*/
 361
 362 MODULE_LICENSE("GPL v2");
 363 MODULE_AUTHOR("Marco Burato <zmaster.adsl@gmail.com>");
 364 MODULE_DESCRIPTION(DRV_DESC);
 365 MODULE_VERSION(DRV_VERSION);