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/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/device.h>
  17 #include <linux/err.h>
  18 #include <linux/gpio/consumer.h>
  19
  20 #include <linux/mmc/host.h>
  21
  22 #include "pwrseq.h"
  23
  24 struct mmc_pwrseq_simple {
  25         struct mmc_pwrseq pwrseq;
  26         bool clk_enabled;
  27         struct clk *ext_clk;
  28         struct gpio_descs *reset_gpios;
  29 };
  30
  31 #define to_pwrseq_simple(p) container_of(p, struct mmc_pwrseq_simple, pwrseq)
  32
  33 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
  34                                               int value)
  35 {
  36         struct gpio_descs *reset_gpios = pwrseq->reset_gpios;
  37
  38         if (!IS_ERR(reset_gpios)) {
  39                 int i;
  40                 int values[reset_gpios->ndescs];
  41
  42                 for (i = 0; i < reset_gpios->ndescs; i++)
  43                         values[i] = value;
  44
  45                 gpiod_set_array_value_cansleep(
  46                         reset_gpios->ndescs, reset_gpios->desc, values);
  47         }
  48 }
  49
  50 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  51 {
  52         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  53
  54         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  55                 clk_prepare_enable(pwrseq->ext_clk);
  56                 pwrseq->clk_enabled = true;
  57         }
  58
  59         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  60 }
  61
  62 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  63 {
  64         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  65
  66         mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  67 }
  68
  69 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  70 {
  71         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  72
  73         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  74
  75         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
  76                 clk_disable_unprepare(pwrseq->ext_clk);
  77                 pwrseq->clk_enabled = false;
  78         }
  79 }
  80
  81 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
  82         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
  83         .post_power_on = mmc_pwrseq_simple_post_power_on,
  84         .power_off = mmc_pwrseq_simple_power_off,
  85 };
  86
  87 static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
  88         { .compatible = "mmc-pwrseq-simple",},
  89         {/* sentinel */},
  90 };
  91 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
  92
  93 static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
  94 {
  95         struct mmc_pwrseq_simple *pwrseq;
  96         struct device *dev = &pdev->dev;
  97
  98         pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
  99         if (!pwrseq)
 100                 return -ENOMEM;
 101
 102         pwrseq->ext_clk = devm_clk_get(dev, "ext_clock");
 103         if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
 104                 return PTR_ERR(pwrseq->ext_clk);
 105
 106         pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset",
 107                                                         GPIOD_OUT_HIGH);
 108         if (IS_ERR(pwrseq->reset_gpios) &&
 109             PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
 110             PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
 111                 return PTR_ERR(pwrseq->reset_gpios);
 112         }
 113
 114         pwrseq->pwrseq.dev = dev;
 115         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 116         pwrseq->pwrseq.owner = THIS_MODULE;
 117         platform_set_drvdata(pdev, pwrseq);
 118
 119         return mmc_pwrseq_register(&pwrseq->pwrseq);
 120 }
 121
 122 static int mmc_pwrseq_simple_remove(struct platform_device *pdev)
 123 {
 124         struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev);
 125
 126         mmc_pwrseq_unregister(&pwrseq->pwrseq);
 127
 128         return 0;
 129 }
 130
 131 static struct platform_driver mmc_pwrseq_simple_driver = {
 132         .probe = mmc_pwrseq_simple_probe,
 133         .remove = mmc_pwrseq_simple_remove,
 134         .driver = {
 135                 .name = "pwrseq_simple",
 136                 .of_match_table = mmc_pwrseq_simple_of_match,
 137         },
 138 };
 139
 140 module_platform_driver(mmc_pwrseq_simple_driver);
 141 MODULE_LICENSE("GPL v2");