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         struct gpio_descs *reset_gpios;
  27 };
  28
  29 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
  30                                               int value)
  31 {
  32         struct gpio_descs *reset_gpios = pwrseq->reset_gpios;
  33
  34         if (!IS_ERR(reset_gpios)) {
  35                 int i;
  36                 int values[reset_gpios->ndescs];
  37
  38                 for (i = 0; i < reset_gpios->ndescs; i++)
  39                         values[i] = value;
  40
  41                 gpiod_set_array_value_cansleep(
  42                         reset_gpios->ndescs, reset_gpios->desc, values);
  43         }
  44 }
  45
  46 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  47 {
  48         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  49                                         struct mmc_pwrseq_simple, pwrseq);
  50
  51         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  52                 clk_prepare_enable(pwrseq->ext_clk);
  53                 pwrseq->clk_enabled = true;
  54         }
  55
  56         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  57 }
  58
  59 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  60 {
  61         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  62                                         struct mmc_pwrseq_simple, pwrseq);
  63
  64         mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  65 }
  66
  67 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  68 {
  69         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  70                                         struct mmc_pwrseq_simple, pwrseq);
  71
  72         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  73
  74         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
  75                 clk_disable_unprepare(pwrseq->ext_clk);
  76                 pwrseq->clk_enabled = false;
  77         }
  78 }
  79
  80 static void mmc_pwrseq_simple_free(struct mmc_host *host)
  81 {
  82         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  83                                         struct mmc_pwrseq_simple, pwrseq);
  84
  85         if (!IS_ERR(pwrseq->reset_gpios))
  86                 gpiod_put_array(pwrseq->reset_gpios);
  87
  88         if (!IS_ERR(pwrseq->ext_clk))
  89                 clk_put(pwrseq->ext_clk);
  90
  91         kfree(pwrseq);
  92 }
  93
  94 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
  95         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
  96         .post_power_on = mmc_pwrseq_simple_post_power_on,
  97         .power_off = mmc_pwrseq_simple_power_off,
  98         .free = mmc_pwrseq_simple_free,
  99 };
 100
 101 struct mmc_pwrseq *mmc_pwrseq_simple_alloc(struct mmc_host *host,
 102                                            struct device *dev)
 103 {
 104         struct mmc_pwrseq_simple *pwrseq;
 105         int ret = 0;
 106
 107         pwrseq = kzalloc(sizeof(*pwrseq), GFP_KERNEL);
 108         if (!pwrseq)
 109                 return ERR_PTR(-ENOMEM);
 110
 111         pwrseq->ext_clk = clk_get(dev, "ext_clock");
 112         if (IS_ERR(pwrseq->ext_clk) &&
 113             PTR_ERR(pwrseq->ext_clk) != -ENOENT) {
 114                 ret = PTR_ERR(pwrseq->ext_clk);
 115                 goto free;
 116         }
 117
 118         pwrseq->reset_gpios = gpiod_get_array(dev, "reset", GPIOD_OUT_HIGH);
 119         if (IS_ERR(pwrseq->reset_gpios) &&
 120             PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
 121             PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
 122                 ret = PTR_ERR(pwrseq->reset_gpios);
 123                 goto clk_put;
 124         }
 125
 126         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 127
 128         return &pwrseq->pwrseq;
 129 clk_put:
 130         if (!IS_ERR(pwrseq->ext_clk))
 131                 clk_put(pwrseq->ext_clk);
 132 free:
 133         kfree(pwrseq);
 134         return ERR_PTR(ret);
 135 }