drivers/mmc/core/pwrseq_simple.c

   1 /*
   2  *  Copyright (C) 2014 Linaro Ltd
   3  *
   4  * Author: Ulf Hansson <ulf.hansson@linaro.org>
   5  *
   6  * License terms: GNU General Public License (GPL) version 2
   7  *
   8  *  Simple MMC power sequence management
   9  */
  10 #include <linux/clk.h>
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/device.h>
  14 #include <linux/err.h>
  15 #include <linux/of_gpio.h>
  16 #include <linux/gpio/consumer.h>
  17
  18 #include <linux/mmc/host.h>
  19
  20 #include "pwrseq.h"
  21
  22 struct mmc_pwrseq_simple {
  23         struct mmc_pwrseq pwrseq;
  24         bool clk_enabled;
  25         struct clk *ext_clk;
  26         int nr_gpios;
  27         struct gpio_desc *reset_gpios[0];
  28 };
  29
  30 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
  31                                               int value)
  32 {
  33         int i;
  34
  35         for (i = 0; i < pwrseq->nr_gpios; i++)
  36                 if (!IS_ERR(pwrseq->reset_gpios[i]))
  37                         gpiod_set_value_cansleep(pwrseq->reset_gpios[i], value);
  38 }
  39
  40 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  41 {
  42         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  43                                         struct mmc_pwrseq_simple, pwrseq);
  44
  45         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  46                 clk_prepare_enable(pwrseq->ext_clk);
  47                 pwrseq->clk_enabled = true;
  48         }
  49
  50         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  51 }
  52
  53 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  54 {
  55         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  56                                         struct mmc_pwrseq_simple, pwrseq);
  57
  58         mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  59 }
  60
  61 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  62 {
  63         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  64                                         struct mmc_pwrseq_simple, pwrseq);
  65
  66         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  67
  68         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
  69                 clk_disable_unprepare(pwrseq->ext_clk);
  70                 pwrseq->clk_enabled = false;
  71         }
  72 }
  73
  74 static void mmc_pwrseq_simple_free(struct mmc_host *host)
  75 {
  76         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  77                                         struct mmc_pwrseq_simple, pwrseq);
  78         int i;
  79
  80         for (i = 0; i < pwrseq->nr_gpios; i++)
  81                 if (!IS_ERR(pwrseq->reset_gpios[i]))
  82                         gpiod_put(pwrseq->reset_gpios[i]);
  83
  84         if (!IS_ERR(pwrseq->ext_clk))
  85                 clk_put(pwrseq->ext_clk);
  86
  87         kfree(pwrseq);
  88         host->pwrseq = NULL;
  89 }
  90
  91 static struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
  92         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
  93         .post_power_on = mmc_pwrseq_simple_post_power_on,
  94         .power_off = mmc_pwrseq_simple_power_off,
  95         .free = mmc_pwrseq_simple_free,
  96 };
  97
  98 int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
  99 {
 100         struct mmc_pwrseq_simple *pwrseq;
 101         int i, nr_gpios, ret = 0;
 102
 103         nr_gpios = of_gpio_named_count(dev->of_node, "reset-gpios");
 104         if (nr_gpios < 0)
 105                 nr_gpios = 0;
 106
 107         pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple) + nr_gpios *
 108                          sizeof(struct gpio_desc *), GFP_KERNEL);
 109         if (!pwrseq)
 110                 return -ENOMEM;
 111
 112         pwrseq->ext_clk = clk_get(dev, "ext_clock");
 113         if (IS_ERR(pwrseq->ext_clk) &&
 114             PTR_ERR(pwrseq->ext_clk) != -ENOENT) {
 115                 ret = PTR_ERR(pwrseq->ext_clk);
 116                 goto free;
 117         }
 118
 119         for (i = 0; i < nr_gpios; i++) {
 120                 pwrseq->reset_gpios[i] = gpiod_get_index(dev, "reset", i,
 121                                                          GPIOD_OUT_HIGH);
 122                 if (IS_ERR(pwrseq->reset_gpios[i]) &&
 123                     PTR_ERR(pwrseq->reset_gpios[i]) != -ENOENT &&
 124                     PTR_ERR(pwrseq->reset_gpios[i]) != -ENOSYS) {
 125                         ret = PTR_ERR(pwrseq->reset_gpios[i]);
 126
 127                         while (i--)
 128                                 gpiod_put(pwrseq->reset_gpios[i]);
 129
 130                         goto clk_put;
 131                 }
 132         }
 133
 134         pwrseq->nr_gpios = nr_gpios;
 135         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 136         host->pwrseq = &pwrseq->pwrseq;
 137
 138         return 0;
 139 clk_put:
 140         if (!IS_ERR(pwrseq->ext_clk))
 141                 clk_put(pwrseq->ext_clk);
 142 free:
 143         kfree(pwrseq);
 144         return ret;
 145 }