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