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, *values;
  44                 int nvalues = reset_gpios->ndescs;
  45
  46                 values = kmalloc_array(nvalues, sizeof(int), GFP_KERNEL);
  47                 if (!values)
  48                         return;
  49
  50                 for (i = 0; i < nvalues; i++)
  51                         values[i] = value;
  52
  53                 gpiod_set_array_value_cansleep(nvalues, reset_gpios->desc, values);
  54                 kfree(values);
  55         }
  56 }
  57
  58 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  59 {
  60         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  61
  62         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  63                 clk_prepare_enable(pwrseq->ext_clk);
  64                 pwrseq->clk_enabled = true;
  65         }
  66
  67         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  68 }
  69
  70 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  71 {
  72         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  73
  74         mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  75
  76         if (pwrseq->post_power_on_delay_ms)
  77                 msleep(pwrseq->post_power_on_delay_ms);
  78 }
  79
  80 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  81 {
  82         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  83
  84         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  85
  86         if (pwrseq->power_off_delay_us)
  87                 usleep_range(pwrseq->power_off_delay_us,
  88                         2 * pwrseq->power_off_delay_us);
  89
  90         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
  91                 clk_disable_unprepare(pwrseq->ext_clk);
  92                 pwrseq->clk_enabled = false;
  93         }
  94 }
  95
  96 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
  97         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
  98         .post_power_on = mmc_pwrseq_simple_post_power_on,
  99         .power_off = mmc_pwrseq_simple_power_off,
 100 };
 101
 102 static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
 103         { .compatible = "mmc-pwrseq-simple",},
 104         {/* sentinel */},
 105 };
 106 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
 107
 108 static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
 109 {
 110         struct mmc_pwrseq_simple *pwrseq;
 111         struct device *dev = &pdev->dev;
 112
 113         pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
 114         if (!pwrseq)
 115                 return -ENOMEM;
 116
 117         pwrseq->ext_clk = devm_clk_get(dev, "ext_clock");
 118         if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
 119                 return PTR_ERR(pwrseq->ext_clk);
 120
 121         pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset",
 122                                                         GPIOD_OUT_HIGH);
 123         if (IS_ERR(pwrseq->reset_gpios) &&
 124             PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
 125             PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
 126                 return PTR_ERR(pwrseq->reset_gpios);
 127         }
 128
 129         device_property_read_u32(dev, "post-power-on-delay-ms",
 130                                  &pwrseq->post_power_on_delay_ms);
 131         device_property_read_u32(dev, "power-off-delay-us",
 132                                  &pwrseq->power_off_delay_us);
 133
 134         pwrseq->pwrseq.dev = dev;
 135         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 136         pwrseq->pwrseq.owner = THIS_MODULE;
 137         platform_set_drvdata(pdev, pwrseq);
 138
 139         return mmc_pwrseq_register(&pwrseq->pwrseq);
 140 }
 141
 142 static int mmc_pwrseq_simple_remove(struct platform_device *pdev)
 143 {
 144         struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev);
 145
 146         mmc_pwrseq_unregister(&pwrseq->pwrseq);
 147
 148         return 0;
 149 }
 150
 151 static struct platform_driver mmc_pwrseq_simple_driver = {
 152         .probe = mmc_pwrseq_simple_probe,
 153         .remove = mmc_pwrseq_simple_remove,
 154         .driver = {
 155                 .name = "pwrseq_simple",
 156                 .of_match_table = mmc_pwrseq_simple_of_match,
 157         },
 158 };
 159
 160 module_platform_driver(mmc_pwrseq_simple_driver);
 161 MODULE_LICENSE("GPL v2");