linux/drivers/gpio/gpio-vx855.c
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   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
  50struct 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 */
  60static 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
  68static 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
  76static 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
  84static 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
  98static 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
 123static 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
 148static 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
 176static 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
 191static 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
 204static 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 = 0;
 218        c->names = vx855gpio_names;
 219}
 220
 221/* This platform device is ordinarily registered by the vx855 mfd driver */
 222static 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
 277out_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        platform_set_drvdata(pdev, NULL);
 283        kfree(vg);
 284        return ret;
 285}
 286
 287static int vx855gpio_remove(struct platform_device *pdev)
 288{
 289        struct vx855_gpio *vg = platform_get_drvdata(pdev);
 290        struct resource *res;
 291
 292        if (gpiochip_remove(&vg->gpio))
 293                dev_err(&pdev->dev, "unable to remove gpio_chip?\n");
 294
 295        if (vg->gpi_reserved) {
 296                res = platform_get_resource(pdev, IORESOURCE_IO, 0);
 297                release_region(res->start, resource_size(res));
 298        }
 299        if (vg->gpo_reserved) {
 300                res = platform_get_resource(pdev, IORESOURCE_IO, 1);
 301                release_region(res->start, resource_size(res));
 302        }
 303
 304        platform_set_drvdata(pdev, NULL);
 305        kfree(vg);
 306        return 0;
 307}
 308
 309static struct platform_driver vx855gpio_driver = {
 310        .driver = {
 311                .name   = MODULE_NAME,
 312                .owner  = THIS_MODULE,
 313        },
 314        .probe          = vx855gpio_probe,
 315        .remove         = vx855gpio_remove,
 316};
 317
 318module_platform_driver(vx855gpio_driver);
 319
 320MODULE_LICENSE("GPL");
 321MODULE_AUTHOR("Harald Welte <HaraldWelte@viatech.com>");
 322MODULE_DESCRIPTION("GPIO driver for the VIA VX855 chipset");
 323MODULE_ALIAS("platform:vx855_gpio");
 324
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