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         u32 power_off_delay_us;
  31         struct clk *ext_clk;
  32         struct gpio_descs *reset_gpios;
  33 };
  34
  35 #define to_pwrseq_simple(p) container_of(p, struct mmc_pwrseq_simple, pwrseq)
  36
  37 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
  38                                               int value)
  39 {
  40         struct gpio_descs *reset_gpios = pwrseq->reset_gpios;
  41
  42         if (!IS_ERR(reset_gpios)) {
  43                 int i;
  44                 int values[reset_gpios->ndescs];
  45
  46                 for (i = 0; i < reset_gpios->ndescs; i++)
  47                         values[i] = value;
  48
  49                 gpiod_set_array_value_cansleep(
  50                         reset_gpios->ndescs, reset_gpios->desc, values);
  51         }
  52 }
  53
  54 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  55 {
  56         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  57
  58         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  59                 clk_prepare_enable(pwrseq->ext_clk);
  60                 pwrseq->clk_enabled = true;
  61         }
  62
  63         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  64 }
  65
  66 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  67 {
  68         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  69
  70         mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  71
  72         if (pwrseq->post_power_on_delay_ms)
  73                 msleep(pwrseq->post_power_on_delay_ms);
  74 }
  75
  76 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  77 {
  78         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  79
  80         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  81
  82         if (pwrseq->power_off_delay_us)
  83                 usleep_range(pwrseq->power_off_delay_us,
  84                         2 * pwrseq->power_off_delay_us);
  85
  86         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
  87                 clk_disable_unprepare(pwrseq->ext_clk);
  88                 pwrseq->clk_enabled = false;
  89         }
  90 }
  91
  92 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
  93         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
  94         .post_power_on = mmc_pwrseq_simple_post_power_on,
  95         .power_off = mmc_pwrseq_simple_power_off,
  96 };
  97
  98 static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
  99         { .compatible = "mmc-pwrseq-simple",},
 100         {/* sentinel */},
 101 };
 102 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
 103
 104 static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
 105 {
 106         struct mmc_pwrseq_simple *pwrseq;
 107         struct device *dev = &pdev->dev;
 108
 109         pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
 110         if (!pwrseq)
 111                 return -ENOMEM;
 112
 113         pwrseq->ext_clk = devm_clk_get(dev, "ext_clock");
 114         if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
 115                 return PTR_ERR(pwrseq->ext_clk);
 116
 117         pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset",
 118                                                         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                 return PTR_ERR(pwrseq->reset_gpios);
 123         }
 124
 125         device_property_read_u32(dev, "post-power-on-delay-ms",
 126                                  &pwrseq->post_power_on_delay_ms);
 127         device_property_read_u32(dev, "power-off-delay-us",
 128                                  &pwrseq->power_off_delay_us);
 129
 130         pwrseq->pwrseq.dev = dev;
 131         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 132         pwrseq->pwrseq.owner = THIS_MODULE;
 133         platform_set_drvdata(pdev, pwrseq);
 134
 135         return mmc_pwrseq_register(&pwrseq->pwrseq);
 136 }
 137
 138 static int mmc_pwrseq_simple_remove(struct platform_device *pdev)
 139 {
 140         struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev);
 141
 142         mmc_pwrseq_unregister(&pwrseq->pwrseq);
 143
 144         return 0;
 145 }
 146
 147 static struct platform_driver mmc_pwrseq_simple_driver = {
 148         .probe = mmc_pwrseq_simple_probe,
 149         .remove = mmc_pwrseq_simple_remove,
 150         .driver = {
 151                 .name = "pwrseq_simple",
 152                 .of_match_table = mmc_pwrseq_simple_of_match,
 153         },
 154 };
 155
 156 module_platform_driver(mmc_pwrseq_simple_driver);
 157 MODULE_LICENSE("GPL v2");