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                 unsigned long *values;
  44                 int nvalues = reset_gpios->ndescs;
  45
  46                 values = bitmap_alloc(nvalues, GFP_KERNEL);
  47                 if (!values)
  48                         return;
  49
  50                 if (value)
  51                         bitmap_fill(values, nvalues);
  52                 else
  53                         bitmap_zero(values, nvalues);
  54
  55                 gpiod_set_array_value_cansleep(nvalues, reset_gpios->desc,
  56                                                reset_gpios->info, values);
  57
  58                 kfree(values);
  59         }
  60 }
  61
  62 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  63 {
  64         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  65
  66         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  67                 clk_prepare_enable(pwrseq->ext_clk);
  68                 pwrseq->clk_enabled = true;
  69         }
  70
  71         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  72 }
  73
  74 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  75 {
  76         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  77
  78         mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  79
  80         if (pwrseq->post_power_on_delay_ms)
  81                 msleep(pwrseq->post_power_on_delay_ms);
  82 }
  83
  84 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  85 {
  86         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  87
  88         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  89
  90         if (pwrseq->power_off_delay_us)
  91                 usleep_range(pwrseq->power_off_delay_us,
  92                         2 * pwrseq->power_off_delay_us);
  93
  94         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
  95                 clk_disable_unprepare(pwrseq->ext_clk);
  96                 pwrseq->clk_enabled = false;
  97         }
  98 }
  99
 100 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
 101         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
 102         .post_power_on = mmc_pwrseq_simple_post_power_on,
 103         .power_off = mmc_pwrseq_simple_power_off,
 104 };
 105
 106 static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
 107         { .compatible = "mmc-pwrseq-simple",},
 108         {/* sentinel */},
 109 };
 110 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
 111
 112 static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
 113 {
 114         struct mmc_pwrseq_simple *pwrseq;
 115         struct device *dev = &pdev->dev;
 116
 117         pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
 118         if (!pwrseq)
 119                 return -ENOMEM;
 120
 121         pwrseq->ext_clk = devm_clk_get(dev, "ext_clock");
 122         if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
 123                 return PTR_ERR(pwrseq->ext_clk);
 124
 125         pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset",
 126                                                         GPIOD_OUT_HIGH);
 127         if (IS_ERR(pwrseq->reset_gpios) &&
 128             PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
 129             PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
 130                 return PTR_ERR(pwrseq->reset_gpios);
 131         }
 132
 133         device_property_read_u32(dev, "post-power-on-delay-ms",
 134                                  &pwrseq->post_power_on_delay_ms);
 135         device_property_read_u32(dev, "power-off-delay-us",
 136                                  &pwrseq->power_off_delay_us);
 137
 138         pwrseq->pwrseq.dev = dev;
 139         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 140         pwrseq->pwrseq.owner = THIS_MODULE;
 141         platform_set_drvdata(pdev, pwrseq);
 142
 143         return mmc_pwrseq_register(&pwrseq->pwrseq);
 144 }
 145
 146 static int mmc_pwrseq_simple_remove(struct platform_device *pdev)
 147 {
 148         struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev);
 149
 150         mmc_pwrseq_unregister(&pwrseq->pwrseq);
 151
 152         return 0;
 153 }
 154
 155 static struct platform_driver mmc_pwrseq_simple_driver = {
 156         .probe = mmc_pwrseq_simple_probe,
 157         .remove = mmc_pwrseq_simple_remove,
 158         .driver = {
 159                 .name = "pwrseq_simple",
 160                 .of_match_table = mmc_pwrseq_simple_of_match,
 161         },
 162 };
 163
 164 module_platform_driver(mmc_pwrseq_simple_driver);
 165 MODULE_LICENSE("GPL v2");