drivers/gpio/basic_mmio_gpio.c

   1 /*
   2  * Driver for basic memory-mapped GPIO controllers.
   3  *
   4  * Copyright 2008 MontaVista Software, Inc.
   5  * Copyright 2008,2010 Anton Vorontsov <cbouatmailru@gmail.com>
   6  *
   7  * This program is free software; you can redistribute  it and/or modify it
   8  * under  the terms of  the GNU General  Public License as published by the
   9  * Free Software Foundation;  either version 2 of the  License, or (at your
  10  * option) any later version.
  11  *
  12  * ....``.```~~~~````.`.`.`.`.```````'',,,.........`````......`.......
  13  * ...``                                                         ```````..
  14  * ..The simplest form of a GPIO controller that the driver supports is``
  15  *  `.just a single "data" register, where GPIO state can be read and/or `
  16  *    `,..written. ,,..``~~~~ .....``.`.`.~~.```.`.........``````.```````
  17  *        `````````
  18                                     ___
  19 _/~~|___/~|   . ```~~~~~~       ___/___\___     ,~.`.`.`.`````.~~...,,,,...
  20 __________|~$@~~~        %~    /o*o*o*o*o*o\   .. Implementing such a GPIO .
  21 o        `                     ~~~~\___/~~~~    ` controller in FPGA is ,.`
  22                                                  `....trivial..'~`.```.```
  23  *                                                    ```````
  24  *  .```````~~~~`..`.``.``.
  25  * .  The driver supports  `...       ,..```.`~~~```````````````....````.``,,
  26  * .   big-endian notation, just`.  .. A bit more sophisticated controllers ,
  27  *  . register the device with -be`. .with a pair of set/clear-bit registers ,
  28  *   `.. suffix.  ```~~`````....`.`   . affecting the data register and the .`
  29  *     ``.`.``...```                  ```.. output pins are also supported.`
  30  *                        ^^             `````.`````````.,``~``~``~~``````
  31  *                                                   .                  ^^
  32  *   ,..`.`.`...````````````......`.`.`.`.`.`..`.`.`..
  33  * .. The expectation is that in at least some cases .    ,-~~~-,
  34  *  .this will be used with roll-your-own ASIC/FPGA .`     \   /
  35  *  .logic in Verilog or VHDL. ~~~`````````..`````~~`       \ /
  36  *  ..````````......```````````                             \o_
  37  *                                                           |
  38  *                              ^^                          / \
  39  *
  40  *           ...`````~~`.....``.`..........``````.`.``.```........``.
  41  *            `  8, 16, 32 and 64 bits registers are supported, and``.
  42  *            . the number of GPIOs is determined by the width of   ~
  43  *             .. the registers. ,............```.`.`..`.`.~~~.`.`.`~
  44  *               `.......````.```
  45  */
  46
  47 #include <linux/init.h>
  48 #include <linux/bug.h>
  49 #include <linux/kernel.h>
  50 #include <linux/module.h>
  51 #include <linux/spinlock.h>
  52 #include <linux/compiler.h>
  53 #include <linux/types.h>
  54 #include <linux/errno.h>
  55 #include <linux/log2.h>
  56 #include <linux/ioport.h>
  57 #include <linux/io.h>
  58 #include <linux/gpio.h>
  59 #include <linux/slab.h>
  60 #include <linux/platform_device.h>
  61 #include <linux/mod_devicetable.h>
  62 #include <linux/basic_mmio_gpio.h>
  63
  64 struct bgpio_chip {
  65         struct gpio_chip gc;
  66         void __iomem *reg_dat;
  67         void __iomem *reg_set;
  68         void __iomem *reg_clr;
  69
  70         /* Number of bits (GPIOs): <register width> * 8. */
  71         int bits;
  72
  73         /*
  74          * Some GPIO controllers work with the big-endian bits notation,
  75          * e.g. in a 8-bits register, GPIO7 is the least significant bit.
  76          */
  77         int big_endian_bits;
  78
  79         /*
  80          * Used to lock bgpio_chip->data. Also, this is needed to keep
  81          * shadowed and real data registers writes together.
  82          */
  83         spinlock_t lock;
  84
  85         /* Shadowed data register to clear/set bits safely. */
  86         unsigned long data;
  87 };
  88
  89 static struct bgpio_chip *to_bgpio_chip(struct gpio_chip *gc)
  90 {
  91         return container_of(gc, struct bgpio_chip, gc);
  92 }
  93
  94 static unsigned long bgpio_in(struct bgpio_chip *bgc)
  95 {
  96         switch (bgc->bits) {
  97         case 8:
  98                 return __raw_readb(bgc->reg_dat);
  99         case 16:
 100                 return __raw_readw(bgc->reg_dat);
 101         case 32:
 102                 return __raw_readl(bgc->reg_dat);
 103 #if BITS_PER_LONG >= 64
 104         case 64:
 105                 return __raw_readq(bgc->reg_dat);
 106 #endif
 107         }
 108         return -EINVAL;
 109 }
 110
 111 static void bgpio_out(struct bgpio_chip *bgc, void __iomem *reg,
 112                       unsigned long data)
 113 {
 114         switch (bgc->bits) {
 115         case 8:
 116                 __raw_writeb(data, reg);
 117                 return;
 118         case 16:
 119                 __raw_writew(data, reg);
 120                 return;
 121         case 32:
 122                 __raw_writel(data, reg);
 123                 return;
 124 #if BITS_PER_LONG >= 64
 125         case 64:
 126                 __raw_writeq(data, reg);
 127                 return;
 128 #endif
 129         }
 130 }
 131
 132 static unsigned long bgpio_pin2mask(struct bgpio_chip *bgc, unsigned int pin)
 133 {
 134         if (bgc->big_endian_bits)
 135                 return 1 << (bgc->bits - 1 - pin);
 136         else
 137                 return 1 << pin;
 138 }
 139
 140 static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
 141 {
 142         struct bgpio_chip *bgc = to_bgpio_chip(gc);
 143
 144         return bgpio_in(bgc) & bgpio_pin2mask(bgc, gpio);
 145 }
 146
 147 static void bgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
 148 {
 149         struct bgpio_chip *bgc = to_bgpio_chip(gc);
 150         unsigned long mask = bgpio_pin2mask(bgc, gpio);
 151         unsigned long flags;
 152
 153         if (bgc->reg_set) {
 154                 if (val)
 155                         bgpio_out(bgc, bgc->reg_set, mask);
 156                 else
 157                         bgpio_out(bgc, bgc->reg_clr, mask);
 158                 return;
 159         }
 160
 161         spin_lock_irqsave(&bgc->lock, flags);
 162
 163         if (val)
 164                 bgc->data |= mask;
 165         else
 166                 bgc->data &= ~mask;
 167
 168         bgpio_out(bgc, bgc->reg_dat, bgc->data);
 169
 170         spin_unlock_irqrestore(&bgc->lock, flags);
 171 }
 172
 173 static int bgpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
 174 {
 175         return 0;
 176 }
 177
 178 static int bgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
 179 {
 180         bgpio_set(gc, gpio, val);
 181         return 0;
 182 }
 183
 184 static int __devinit bgpio_probe(struct platform_device *pdev)
 185 {
 186         const struct platform_device_id *platid = platform_get_device_id(pdev);
 187         struct device *dev = &pdev->dev;
 188         struct bgpio_pdata *pdata = dev_get_platdata(dev);
 189         struct bgpio_chip *bgc;
 190         struct resource *res_dat;
 191         struct resource *res_set;
 192         struct resource *res_clr;
 193         resource_size_t dat_sz;
 194         int bits;
 195         int ret;
 196
 197         res_dat = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
 198         if (!res_dat)
 199                 return -EINVAL;
 200
 201         dat_sz = resource_size(res_dat);
 202         if (!is_power_of_2(dat_sz))
 203                 return -EINVAL;
 204
 205         bits = dat_sz * 8;
 206         if (bits > BITS_PER_LONG)
 207                 return -EINVAL;
 208
 209         bgc = devm_kzalloc(dev, sizeof(*bgc), GFP_KERNEL);
 210         if (!bgc)
 211                 return -ENOMEM;
 212
 213         bgc->reg_dat = devm_ioremap(dev, res_dat->start, dat_sz);
 214         if (!bgc->reg_dat)
 215                 return -ENOMEM;
 216
 217         res_set = platform_get_resource_byname(pdev, IORESOURCE_MEM, "set");
 218         res_clr = platform_get_resource_byname(pdev, IORESOURCE_MEM, "clr");
 219         if (res_set && res_clr) {
 220                 if (resource_size(res_set) != resource_size(res_clr) ||
 221                                 resource_size(res_set) != dat_sz)
 222                         return -EINVAL;
 223
 224                 bgc->reg_set = devm_ioremap(dev, res_set->start, dat_sz);
 225                 bgc->reg_clr = devm_ioremap(dev, res_clr->start, dat_sz);
 226                 if (!bgc->reg_set || !bgc->reg_clr)
 227                         return -ENOMEM;
 228         } else if (res_set || res_clr) {
 229                 return -EINVAL;
 230         }
 231
 232         spin_lock_init(&bgc->lock);
 233
 234         bgc->bits = bits;
 235         bgc->big_endian_bits = !strcmp(platid->name, "basic-mmio-gpio-be");
 236         bgc->data = bgpio_in(bgc);
 237
 238         bgc->gc.ngpio = bits;
 239         bgc->gc.direction_input = bgpio_dir_in;
 240         bgc->gc.direction_output = bgpio_dir_out;
 241         bgc->gc.get = bgpio_get;
 242         bgc->gc.set = bgpio_set;
 243         bgc->gc.dev = dev;
 244         bgc->gc.label = dev_name(dev);
 245
 246         if (pdata)
 247                 bgc->gc.base = pdata->base;
 248         else
 249                 bgc->gc.base = -1;
 250
 251         dev_set_drvdata(dev, bgc);
 252
 253         ret = gpiochip_add(&bgc->gc);
 254         if (ret)
 255                 dev_err(dev, "gpiochip_add() failed: %d\n", ret);
 256
 257         return ret;
 258 }
 259
 260 static int __devexit bgpio_remove(struct platform_device *pdev)
 261 {
 262         struct bgpio_chip *bgc = dev_get_drvdata(&pdev->dev);
 263
 264         return gpiochip_remove(&bgc->gc);
 265 }
 266
 267 static const struct platform_device_id bgpio_id_table[] = {
 268         { "basic-mmio-gpio", },
 269         { "basic-mmio-gpio-be", },
 270         {},
 271 };
 272 MODULE_DEVICE_TABLE(platform, bgpio_id_table);
 273
 274 static struct platform_driver bgpio_driver = {
 275         .driver = {
 276                 .name = "basic-mmio-gpio",
 277         },
 278         .id_table = bgpio_id_table,
 279         .probe = bgpio_probe,
 280         .remove = __devexit_p(bgpio_remove),
 281 };
 282
 283 static int __init bgpio_init(void)
 284 {
 285         return platform_driver_register(&bgpio_driver);
 286 }
 287 module_init(bgpio_init);
 288
 289 static void __exit bgpio_exit(void)
 290 {
 291         platform_driver_unregister(&bgpio_driver);
 292 }
 293 module_exit(bgpio_exit);
 294
 295 MODULE_DESCRIPTION("Driver for basic memory-mapped GPIO controllers");
 296 MODULE_AUTHOR("Anton Vorontsov <cbouatmailru@gmail.com>");
 297 MODULE_LICENSE("GPL");