drivers/mmc/core/slot-gpio.c

   1 /*
   2  * Generic GPIO card-detect helper
   3  *
   4  * Copyright (C) 2011, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
   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
  11 #include <linux/err.h>
  12 #include <linux/gpio.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/jiffies.h>
  15 #include <linux/mmc/host.h>
  16 #include <linux/mmc/slot-gpio.h>
  17 #include <linux/module.h>
  18 #include <linux/slab.h>
  19
  20 struct mmc_gpio {
  21         int ro_gpio;
  22         int cd_gpio;
  23         char *ro_label;
  24         char cd_label[0];
  25 };
  26
  27 static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
  28 {
  29         /* Schedule a card detection after a debounce timeout */
  30         struct mmc_host *host = dev_id;
  31
  32         if (host->ops->card_event)
  33                 host->ops->card_event(host);
  34
  35         mmc_detect_change(host, msecs_to_jiffies(200));
  36
  37         return IRQ_HANDLED;
  38 }
  39
  40 static int mmc_gpio_alloc(struct mmc_host *host)
  41 {
  42         size_t len = strlen(dev_name(host->parent)) + 4;
  43         struct mmc_gpio *ctx;
  44
  45         mutex_lock(&host->slot.lock);
  46
  47         ctx = host->slot.handler_priv;
  48         if (!ctx) {
  49                 /*
  50                  * devm_kzalloc() can be called after device_initialize(), even
  51                  * before device_add(), i.e., between mmc_alloc_host() and
  52                  * mmc_add_host()
  53                  */
  54                 ctx = devm_kzalloc(&host->class_dev, sizeof(*ctx) + 2 * len,
  55                                    GFP_KERNEL);
  56                 if (ctx) {
  57                         ctx->ro_label = ctx->cd_label + len;
  58                         snprintf(ctx->cd_label, len, "%s cd", dev_name(host->parent));
  59                         snprintf(ctx->ro_label, len, "%s ro", dev_name(host->parent));
  60                         ctx->cd_gpio = -EINVAL;
  61                         ctx->ro_gpio = -EINVAL;
  62                         host->slot.handler_priv = ctx;
  63                 }
  64         }
  65
  66         mutex_unlock(&host->slot.lock);
  67
  68         return ctx ? 0 : -ENOMEM;
  69 }
  70
  71 int mmc_gpio_get_ro(struct mmc_host *host)
  72 {
  73         struct mmc_gpio *ctx = host->slot.handler_priv;
  74
  75         if (!ctx || !gpio_is_valid(ctx->ro_gpio))
  76                 return -ENOSYS;
  77
  78         return !gpio_get_value_cansleep(ctx->ro_gpio) ^
  79                 !!(host->caps2 & MMC_CAP2_RO_ACTIVE_HIGH);
  80 }
  81 EXPORT_SYMBOL(mmc_gpio_get_ro);
  82
  83 int mmc_gpio_get_cd(struct mmc_host *host)
  84 {
  85         struct mmc_gpio *ctx = host->slot.handler_priv;
  86
  87         if (!ctx || !gpio_is_valid(ctx->cd_gpio))
  88                 return -ENOSYS;
  89
  90         return !gpio_get_value_cansleep(ctx->cd_gpio) ^
  91                 !!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);
  92 }
  93 EXPORT_SYMBOL(mmc_gpio_get_cd);
  94
  95 /**
  96  * mmc_gpio_request_ro - request a gpio for write-protection
  97  * @host: mmc host
  98  * @gpio: gpio number requested
  99  *
 100  * As devm_* managed functions are used in mmc_gpio_request_ro(), client
 101  * drivers do not need to explicitly call mmc_gpio_free_ro() for freeing up,
 102  * if the requesting and freeing are only needed at probing and unbinding time
 103  * for once.  However, if client drivers do something special like runtime
 104  * switching for write-protection, they are responsible for calling
 105  * mmc_gpio_request_ro() and mmc_gpio_free_ro() as a pair on their own.
 106  *
 107  * Returns zero on success, else an error.
 108  */
 109 int mmc_gpio_request_ro(struct mmc_host *host, unsigned int gpio)
 110 {
 111         struct mmc_gpio *ctx;
 112         int ret;
 113
 114         if (!gpio_is_valid(gpio))
 115                 return -EINVAL;
 116
 117         ret = mmc_gpio_alloc(host);
 118         if (ret < 0)
 119                 return ret;
 120
 121         ctx = host->slot.handler_priv;
 122
 123         ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
 124                                     ctx->ro_label);
 125         if (ret < 0)
 126                 return ret;
 127
 128         ctx->ro_gpio = gpio;
 129
 130         return 0;
 131 }
 132 EXPORT_SYMBOL(mmc_gpio_request_ro);
 133
 134 /**
 135  * mmc_gpio_request_cd - request a gpio for card-detection
 136  * @host: mmc host
 137  * @gpio: gpio number requested
 138  * @debounce: debounce time in microseconds
 139  *
 140  * As devm_* managed functions are used in mmc_gpio_request_cd(), client
 141  * drivers do not need to explicitly call mmc_gpio_free_cd() for freeing up,
 142  * if the requesting and freeing are only needed at probing and unbinding time
 143  * for once.  However, if client drivers do something special like runtime
 144  * switching for card-detection, they are responsible for calling
 145  * mmc_gpio_request_cd() and mmc_gpio_free_cd() as a pair on their own.
 146  *
 147  * If GPIO debouncing is desired, set the debounce parameter to a non-zero
 148  * value. The caller is responsible for ensuring that the GPIO driver associated
 149  * with the GPIO supports debouncing, otherwise an error will be returned.
 150  *
 151  * Returns zero on success, else an error.
 152  */
 153 int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio,
 154                         unsigned int debounce)
 155 {
 156         struct mmc_gpio *ctx;
 157         int irq = gpio_to_irq(gpio);
 158         int ret;
 159
 160         ret = mmc_gpio_alloc(host);
 161         if (ret < 0)
 162                 return ret;
 163
 164         ctx = host->slot.handler_priv;
 165
 166         ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
 167                                     ctx->cd_label);
 168         if (ret < 0)
 169                 /*
 170                  * don't bother freeing memory. It might still get used by other
 171                  * slot functions, in any case it will be freed, when the device
 172                  * is destroyed.
 173                  */
 174                 return ret;
 175
 176         if (debounce) {
 177                 ret = gpio_set_debounce(gpio, debounce);
 178                 if (ret < 0)
 179                         return ret;
 180         }
 181
 182         /*
 183          * Even if gpio_to_irq() returns a valid IRQ number, the platform might
 184          * still prefer to poll, e.g., because that IRQ number is already used
 185          * by another unit and cannot be shared.
 186          */
 187         if (irq >= 0 && host->caps & MMC_CAP_NEEDS_POLL)
 188                 irq = -EINVAL;
 189
 190         if (irq >= 0) {
 191                 ret = devm_request_threaded_irq(&host->class_dev, irq,
 192                         NULL, mmc_gpio_cd_irqt,
 193                         IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
 194                         ctx->cd_label, host);
 195                 if (ret < 0)
 196                         irq = ret;
 197         }
 198
 199         host->slot.cd_irq = irq;
 200
 201         if (irq < 0)
 202                 host->caps |= MMC_CAP_NEEDS_POLL;
 203
 204         ctx->cd_gpio = gpio;
 205
 206         return 0;
 207 }
 208 EXPORT_SYMBOL(mmc_gpio_request_cd);
 209
 210 /**
 211  * mmc_gpio_free_ro - free the write-protection gpio
 212  * @host: mmc host
 213  *
 214  * It's provided only for cases that client drivers need to manually free
 215  * up the write-protection gpio requested by mmc_gpio_request_ro().
 216  */
 217 void mmc_gpio_free_ro(struct mmc_host *host)
 218 {
 219         struct mmc_gpio *ctx = host->slot.handler_priv;
 220         int gpio;
 221
 222         if (!ctx || !gpio_is_valid(ctx->ro_gpio))
 223                 return;
 224
 225         gpio = ctx->ro_gpio;
 226         ctx->ro_gpio = -EINVAL;
 227
 228         devm_gpio_free(&host->class_dev, gpio);
 229 }
 230 EXPORT_SYMBOL(mmc_gpio_free_ro);
 231
 232 /**
 233  * mmc_gpio_free_cd - free the card-detection gpio
 234  * @host: mmc host
 235  *
 236  * It's provided only for cases that client drivers need to manually free
 237  * up the card-detection gpio requested by mmc_gpio_request_cd().
 238  */
 239 void mmc_gpio_free_cd(struct mmc_host *host)
 240 {
 241         struct mmc_gpio *ctx = host->slot.handler_priv;
 242         int gpio;
 243
 244         if (!ctx || !gpio_is_valid(ctx->cd_gpio))
 245                 return;
 246
 247         if (host->slot.cd_irq >= 0) {
 248                 devm_free_irq(&host->class_dev, host->slot.cd_irq, host);
 249                 host->slot.cd_irq = -EINVAL;
 250         }
 251
 252         gpio = ctx->cd_gpio;
 253         ctx->cd_gpio = -EINVAL;
 254
 255         devm_gpio_free(&host->class_dev, gpio);
 256 }
 257 EXPORT_SYMBOL(mmc_gpio_free_cd);