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 #include <linux/delay.h>
  20 #include <linux/property.h>
  21
  22 #include <linux/mmc/host.h>
  23
  24 #include "pwrseq.h"
  25
  26 struct mmc_pwrseq_simple {
  27         struct mmc_pwrseq pwrseq;
  28         bool clk_enabled;
  29         u32 post_power_on_delay_ms;
  30         struct clk *ext_clk;
  31         struct gpio_descs *reset_gpios;
  32 };
  33
  34 #define to_pwrseq_simple(p) container_of(p, struct mmc_pwrseq_simple, pwrseq)
  35
  36 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
  37                                               int value)
  38 {
  39         struct gpio_descs *reset_gpios = pwrseq->reset_gpios;
  40
  41         if (!IS_ERR(reset_gpios)) {
  42                 int i;
  43                 int values[reset_gpios->ndescs];
  44
  45                 for (i = 0; i < reset_gpios->ndescs; i++)
  46                         values[i] = value;
  47
  48                 gpiod_set_array_value_cansleep(
  49                         reset_gpios->ndescs, reset_gpios->desc, values);
  50         }
  51 }
  52
  53 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  54 {
  55         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  56
  57         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  58                 clk_prepare_enable(pwrseq->ext_clk);
  59                 pwrseq->clk_enabled = true;
  60         }
  61
  62         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  63 }
  64
  65 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  66 {
  67         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  68
  69         mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  70
  71         if (pwrseq->post_power_on_delay_ms)
  72                 msleep(pwrseq->post_power_on_delay_ms);
  73 }
  74
  75 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  76 {
  77         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  78
  79         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  80
  81         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
  82                 clk_disable_unprepare(pwrseq->ext_clk);
  83                 pwrseq->clk_enabled = false;
  84         }
  85 }
  86
  87 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
  88         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
  89         .post_power_on = mmc_pwrseq_simple_post_power_on,
  90         .power_off = mmc_pwrseq_simple_power_off,
  91 };
  92
  93 static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
  94         { .compatible = "mmc-pwrseq-simple",},
  95         {/* sentinel */},
  96 };
  97 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
  98
  99 static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
 100 {
 101         struct mmc_pwrseq_simple *pwrseq;
 102         struct device *dev = &pdev->dev;
 103
 104         pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
 105         if (!pwrseq)
 106                 return -ENOMEM;
 107
 108         pwrseq->ext_clk = devm_clk_get(dev, "ext_clock");
 109         if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
 110                 return PTR_ERR(pwrseq->ext_clk);
 111
 112         pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset",
 113                                                         GPIOD_OUT_HIGH);
 114         if (IS_ERR(pwrseq->reset_gpios) &&
 115             PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
 116             PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
 117                 return PTR_ERR(pwrseq->reset_gpios);
 118         }
 119
 120         device_property_read_u32(dev, "post-power-on-delay-ms",
 121                                  &pwrseq->post_power_on_delay_ms);
 122
 123         pwrseq->pwrseq.dev = dev;
 124         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 125         pwrseq->pwrseq.owner = THIS_MODULE;
 126         platform_set_drvdata(pdev, pwrseq);
 127
 128         return mmc_pwrseq_register(&pwrseq->pwrseq);
 129 }
 130
 131 static int mmc_pwrseq_simple_remove(struct platform_device *pdev)
 132 {
 133         struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev);
 134
 135         mmc_pwrseq_unregister(&pwrseq->pwrseq);
 136
 137         return 0;
 138 }
 139
 140 static struct platform_driver mmc_pwrseq_simple_driver = {
 141         .probe = mmc_pwrseq_simple_probe,
 142         .remove = mmc_pwrseq_simple_remove,
 143         .driver = {
 144                 .name = "pwrseq_simple",
 145                 .of_match_table = mmc_pwrseq_simple_of_match,
 146         },
 147 };
 148
 149 module_platform_driver(mmc_pwrseq_simple_driver);
 150 MODULE_LICENSE("GPL v2");