drivers/gpio/gpio-vx855.c

   1 /*
   2  * Linux GPIOlib driver for the VIA VX855 integrated southbridge GPIO
   3  *
   4  * Copyright (C) 2009 VIA Technologies, Inc.
   5  * Copyright (C) 2010 One Laptop per Child
   6  * Author: Harald Welte <HaraldWelte@viatech.com>
   7  * All rights reserved.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation; either version 2 of
  12  * the License, or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  22  * MA 02111-1307 USA
  23  *
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28 #include <linux/gpio.h>
  29 #include <linux/slab.h>
  30 #include <linux/device.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/pci.h>
  33 #include <linux/io.h>
  34
  35 #define MODULE_NAME "vx855_gpio"
  36
  37 /* The VX855 south bridge has the following GPIO pins:
  38  *      GPI 0...13      General Purpose Input
  39  *      GPO 0...12      General Purpose Output
  40  *      GPIO 0...14     General Purpose I/O (Open-Drain)
  41  */
  42
  43 #define NR_VX855_GPI    14
  44 #define NR_VX855_GPO    13
  45 #define NR_VX855_GPIO   15
  46
  47 #define NR_VX855_GPInO  (NR_VX855_GPI + NR_VX855_GPO)
  48 #define NR_VX855_GP     (NR_VX855_GPI + NR_VX855_GPO + NR_VX855_GPIO)
  49
  50 struct vx855_gpio {
  51         struct gpio_chip gpio;
  52         spinlock_t lock;
  53         u32 io_gpi;
  54         u32 io_gpo;
  55         bool gpi_reserved;
  56         bool gpo_reserved;
  57 };
  58
  59 /* resolve a GPIx into the corresponding bit position */
  60 static inline u_int32_t gpi_i_bit(int i)
  61 {
  62         if (i < 10)
  63                 return 1 << i;
  64         else
  65                 return 1 << (i + 14);
  66 }
  67
  68 static inline u_int32_t gpo_o_bit(int i)
  69 {
  70         if (i < 11)
  71                 return 1 << i;
  72         else
  73                 return 1 << (i + 14);
  74 }
  75
  76 static inline u_int32_t gpio_i_bit(int i)
  77 {
  78         if (i < 14)
  79                 return 1 << (i + 10);
  80         else
  81                 return 1 << (i + 14);
  82 }
  83
  84 static inline u_int32_t gpio_o_bit(int i)
  85 {
  86         if (i < 14)
  87                 return 1 << (i + 11);
  88         else
  89                 return 1 << (i + 13);
  90 }
  91
  92 /* Mapping betwee numeric GPIO ID and the actual GPIO hardware numbering:
  93  * 0..13        GPI 0..13
  94  * 14..26       GPO 0..12
  95  * 27..41       GPIO 0..14
  96  */
  97
  98 static int vx855gpio_direction_input(struct gpio_chip *gpio,
  99                                      unsigned int nr)
 100 {
 101         struct vx855_gpio *vg = container_of(gpio, struct vx855_gpio, gpio);
 102         unsigned long flags;
 103         u_int32_t reg_out;
 104
 105         /* Real GPI bits are always in input direction */
 106         if (nr < NR_VX855_GPI)
 107                 return 0;
 108
 109         /* Real GPO bits cannot be put in output direction */
 110         if (nr < NR_VX855_GPInO)
 111                 return -EINVAL;
 112
 113         /* Open Drain GPIO have to be set to one */
 114         spin_lock_irqsave(&vg->lock, flags);
 115         reg_out = inl(vg->io_gpo);
 116         reg_out |= gpio_o_bit(nr - NR_VX855_GPInO);
 117         outl(reg_out, vg->io_gpo);
 118         spin_unlock_irqrestore(&vg->lock, flags);
 119
 120         return 0;
 121 }
 122
 123 static int vx855gpio_get(struct gpio_chip *gpio, unsigned int nr)
 124 {
 125         struct vx855_gpio *vg = container_of(gpio, struct vx855_gpio, gpio);
 126         u_int32_t reg_in;
 127         int ret = 0;
 128
 129         if (nr < NR_VX855_GPI) {
 130                 reg_in = inl(vg->io_gpi);
 131                 if (reg_in & gpi_i_bit(nr))
 132                         ret = 1;
 133         } else if (nr < NR_VX855_GPInO) {
 134                 /* GPO don't have an input bit, we need to read it
 135                  * back from the output register */
 136                 reg_in = inl(vg->io_gpo);
 137                 if (reg_in & gpo_o_bit(nr - NR_VX855_GPI))
 138                         ret = 1;
 139         } else {
 140                 reg_in = inl(vg->io_gpi);
 141                 if (reg_in & gpio_i_bit(nr - NR_VX855_GPInO))
 142                         ret = 1;
 143         }
 144
 145         return ret;
 146 }
 147
 148 static void vx855gpio_set(struct gpio_chip *gpio, unsigned int nr,
 149                           int val)
 150 {
 151         struct vx855_gpio *vg = container_of(gpio, struct vx855_gpio, gpio);
 152         unsigned long flags;
 153         u_int32_t reg_out;
 154
 155         /* True GPI cannot be switched to output mode */
 156         if (nr < NR_VX855_GPI)
 157                 return;
 158
 159         spin_lock_irqsave(&vg->lock, flags);
 160         reg_out = inl(vg->io_gpo);
 161         if (nr < NR_VX855_GPInO) {
 162                 if (val)
 163                         reg_out |= gpo_o_bit(nr - NR_VX855_GPI);
 164                 else
 165                         reg_out &= ~gpo_o_bit(nr - NR_VX855_GPI);
 166         } else {
 167                 if (val)
 168                         reg_out |= gpio_o_bit(nr - NR_VX855_GPInO);
 169                 else
 170                         reg_out &= ~gpio_o_bit(nr - NR_VX855_GPInO);
 171         }
 172         outl(reg_out, vg->io_gpo);
 173         spin_unlock_irqrestore(&vg->lock, flags);
 174 }
 175
 176 static int vx855gpio_direction_output(struct gpio_chip *gpio,
 177                                       unsigned int nr, int val)
 178 {
 179         /* True GPI cannot be switched to output mode */
 180         if (nr < NR_VX855_GPI)
 181                 return -EINVAL;
 182
 183         /* True GPO don't need to be switched to output mode,
 184          * and GPIO are open-drain, i.e. also need no switching,
 185          * so all we do is set the level */
 186         vx855gpio_set(gpio, nr, val);
 187
 188         return 0;
 189 }
 190
 191 static const char *vx855gpio_names[NR_VX855_GP] = {
 192         "VX855_GPI0", "VX855_GPI1", "VX855_GPI2", "VX855_GPI3", "VX855_GPI4",
 193         "VX855_GPI5", "VX855_GPI6", "VX855_GPI7", "VX855_GPI8", "VX855_GPI9",
 194         "VX855_GPI10", "VX855_GPI11", "VX855_GPI12", "VX855_GPI13",
 195         "VX855_GPO0", "VX855_GPO1", "VX855_GPO2", "VX855_GPO3", "VX855_GPO4",
 196         "VX855_GPO5", "VX855_GPO6", "VX855_GPO7", "VX855_GPO8", "VX855_GPO9",
 197         "VX855_GPO10", "VX855_GPO11", "VX855_GPO12",
 198         "VX855_GPIO0", "VX855_GPIO1", "VX855_GPIO2", "VX855_GPIO3",
 199         "VX855_GPIO4", "VX855_GPIO5", "VX855_GPIO6", "VX855_GPIO7",
 200         "VX855_GPIO8", "VX855_GPIO9", "VX855_GPIO10", "VX855_GPIO11",
 201         "VX855_GPIO12", "VX855_GPIO13", "VX855_GPIO14"
 202 };
 203
 204 static void vx855gpio_gpio_setup(struct vx855_gpio *vg)
 205 {
 206         struct gpio_chip *c = &vg->gpio;
 207
 208         c->label = "VX855 South Bridge";
 209         c->owner = THIS_MODULE;
 210         c->direction_input = vx855gpio_direction_input;
 211         c->direction_output = vx855gpio_direction_output;
 212         c->get = vx855gpio_get;
 213         c->set = vx855gpio_set;
 214         c->dbg_show = NULL;
 215         c->base = 0;
 216         c->ngpio = NR_VX855_GP;
 217         c->can_sleep = false;
 218         c->names = vx855gpio_names;
 219 }
 220
 221 /* This platform device is ordinarily registered by the vx855 mfd driver */
 222 static int vx855gpio_probe(struct platform_device *pdev)
 223 {
 224         struct resource *res_gpi;
 225         struct resource *res_gpo;
 226         struct vx855_gpio *vg;
 227         int ret;
 228
 229         res_gpi = platform_get_resource(pdev, IORESOURCE_IO, 0);
 230         res_gpo = platform_get_resource(pdev, IORESOURCE_IO, 1);
 231         if (!res_gpi || !res_gpo)
 232                 return -EBUSY;
 233
 234         vg = kzalloc(sizeof(*vg), GFP_KERNEL);
 235         if (!vg)
 236                 return -ENOMEM;
 237
 238         platform_set_drvdata(pdev, vg);
 239
 240         dev_info(&pdev->dev, "found VX855 GPIO controller\n");
 241         vg->io_gpi = res_gpi->start;
 242         vg->io_gpo = res_gpo->start;
 243         spin_lock_init(&vg->lock);
 244
 245         /*
 246          * A single byte is used to control various GPIO ports on the VX855,
 247          * and in the case of the OLPC XO-1.5, some of those ports are used
 248          * for switches that are interpreted and exposed through ACPI. ACPI
 249          * will have reserved the region, so our own reservation will not
 250          * succeed. Ignore and continue.
 251          */
 252
 253         if (!request_region(res_gpi->start, resource_size(res_gpi),
 254                         MODULE_NAME "_gpi"))
 255                 dev_warn(&pdev->dev,
 256                         "GPI I/O resource busy, probably claimed by ACPI\n");
 257         else
 258                 vg->gpi_reserved = true;
 259
 260         if (!request_region(res_gpo->start, resource_size(res_gpo),
 261                         MODULE_NAME "_gpo"))
 262                 dev_warn(&pdev->dev,
 263                         "GPO I/O resource busy, probably claimed by ACPI\n");
 264         else
 265                 vg->gpo_reserved = true;
 266
 267         vx855gpio_gpio_setup(vg);
 268
 269         ret = gpiochip_add(&vg->gpio);
 270         if (ret) {
 271                 dev_err(&pdev->dev, "failed to register GPIOs\n");
 272                 goto out_release;
 273         }
 274
 275         return 0;
 276
 277 out_release:
 278         if (vg->gpi_reserved)
 279                 release_region(res_gpi->start, resource_size(res_gpi));
 280         if (vg->gpo_reserved)
 281                 release_region(res_gpi->start, resource_size(res_gpo));
 282         kfree(vg);
 283         return ret;
 284 }
 285
 286 static int vx855gpio_remove(struct platform_device *pdev)
 287 {
 288         struct vx855_gpio *vg = platform_get_drvdata(pdev);
 289         struct resource *res;
 290
 291         gpiochip_remove(&vg->gpio);
 292
 293         if (vg->gpi_reserved) {
 294                 res = platform_get_resource(pdev, IORESOURCE_IO, 0);
 295                 release_region(res->start, resource_size(res));
 296         }
 297         if (vg->gpo_reserved) {
 298                 res = platform_get_resource(pdev, IORESOURCE_IO, 1);
 299                 release_region(res->start, resource_size(res));
 300         }
 301
 302         kfree(vg);
 303         return 0;
 304 }
 305
 306 static struct platform_driver vx855gpio_driver = {
 307         .driver = {
 308                 .name   = MODULE_NAME,
 309                 .owner  = THIS_MODULE,
 310         },
 311         .probe          = vx855gpio_probe,
 312         .remove         = vx855gpio_remove,
 313 };
 314
 315 module_platform_driver(vx855gpio_driver);
 316
 317 MODULE_LICENSE("GPL");
 318 MODULE_AUTHOR("Harald Welte <HaraldWelte@viatech.com>");
 319 MODULE_DESCRIPTION("GPIO driver for the VIA VX855 chipset");
 320 MODULE_ALIAS("platform:vx855_gpio");