drivers/mmc/core/pwrseq_simple.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Copyright (C) 2014 Linaro Ltd
   4  *
   5  * Author: Ulf Hansson <ulf.hansson@linaro.org>
   6  *
   7  *  Simple MMC power sequence management
   8  */
   9 #include <linux/clk.h>
  10 #include <linux/init.h>
  11 #include <linux/kernel.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/device.h>
  16 #include <linux/err.h>
  17 #include <linux/gpio/consumer.h>
  18 #include <linux/delay.h>
  19 #include <linux/property.h>
  20 #include <linux/of.h>
  21 #include <linux/reset.h>
  22
  23 #include <linux/mmc/host.h>
  24
  25 #include "pwrseq.h"
  26
  27 struct mmc_pwrseq_simple {
  28         struct mmc_pwrseq pwrseq;
  29         bool clk_enabled;
  30         u32 post_power_on_delay_ms;
  31         u32 power_off_delay_us;
  32         struct clk *ext_clk;
  33         struct gpio_descs *reset_gpios;
  34         struct reset_control *reset_ctrl;
  35 };
  36
  37 #define to_pwrseq_simple(p) container_of(p, struct mmc_pwrseq_simple, pwrseq)
  38
  39 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
  40                                               int value)
  41 {
  42         struct gpio_descs *reset_gpios = pwrseq->reset_gpios;
  43
  44         if (!IS_ERR(reset_gpios)) {
  45                 unsigned long *values;
  46                 int nvalues = reset_gpios->ndescs;
  47
  48                 values = bitmap_alloc(nvalues, GFP_KERNEL);
  49                 if (!values)
  50                         return;
  51
  52                 if (value)
  53                         bitmap_fill(values, nvalues);
  54                 else
  55                         bitmap_zero(values, nvalues);
  56
  57                 gpiod_set_array_value_cansleep(nvalues, reset_gpios->desc,
  58                                                reset_gpios->info, values);
  59
  60                 bitmap_free(values);
  61         }
  62 }
  63
  64 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  65 {
  66         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  67
  68         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  69                 clk_prepare_enable(pwrseq->ext_clk);
  70                 pwrseq->clk_enabled = true;
  71         }
  72
  73         if (pwrseq->reset_ctrl) {
  74                 reset_control_deassert(pwrseq->reset_ctrl);
  75                 reset_control_assert(pwrseq->reset_ctrl);
  76         } else
  77                 mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  78 }
  79
  80 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  81 {
  82         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  83
  84         if (pwrseq->reset_ctrl)
  85                 reset_control_deassert(pwrseq->reset_ctrl);
  86         else
  87                 mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  88
  89         if (pwrseq->post_power_on_delay_ms)
  90                 msleep(pwrseq->post_power_on_delay_ms);
  91 }
  92
  93 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  94 {
  95         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
  96
  97         if (pwrseq->reset_ctrl)
  98                 reset_control_assert(pwrseq->reset_ctrl);
  99         else
 100                 mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
 101
 102         if (pwrseq->power_off_delay_us)
 103                 usleep_range(pwrseq->power_off_delay_us,
 104                         2 * pwrseq->power_off_delay_us);
 105
 106         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
 107                 clk_disable_unprepare(pwrseq->ext_clk);
 108                 pwrseq->clk_enabled = false;
 109         }
 110 }
 111
 112 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
 113         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
 114         .post_power_on = mmc_pwrseq_simple_post_power_on,
 115         .power_off = mmc_pwrseq_simple_power_off,
 116 };
 117
 118 static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
 119         { .compatible = "mmc-pwrseq-simple",},
 120         {/* sentinel */},
 121 };
 122 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
 123
 124 static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
 125 {
 126         struct mmc_pwrseq_simple *pwrseq;
 127         struct device *dev = &pdev->dev;
 128         int ngpio;
 129
 130         pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
 131         if (!pwrseq)
 132                 return -ENOMEM;
 133
 134         pwrseq->ext_clk = devm_clk_get(dev, "ext_clock");
 135         if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
 136                 return dev_err_probe(dev, PTR_ERR(pwrseq->ext_clk), "external clock not ready\n");
 137
 138         ngpio = of_count_phandle_with_args(dev->of_node, "reset-gpios", "#gpio-cells");
 139         if (ngpio == 1) {
 140                 pwrseq->reset_ctrl = devm_reset_control_get_optional_shared(dev, NULL);
 141                 if (IS_ERR(pwrseq->reset_ctrl))
 142                         return dev_err_probe(dev, PTR_ERR(pwrseq->reset_ctrl),
 143                                              "reset control not ready\n");
 144         }
 145
 146         /*
 147          * Fallback to GPIO based reset control in case of multiple reset lines
 148          * are specified or the platform doesn't have support for RESET at all.
 149          */
 150         if (!pwrseq->reset_ctrl) {
 151                 pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset", GPIOD_OUT_HIGH);
 152                 if (IS_ERR(pwrseq->reset_gpios) &&
 153                     PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
 154                     PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
 155                         return dev_err_probe(dev, PTR_ERR(pwrseq->reset_gpios),
 156                                              "reset GPIOs not ready\n");
 157                 }
 158         }
 159
 160         device_property_read_u32(dev, "post-power-on-delay-ms",
 161                                  &pwrseq->post_power_on_delay_ms);
 162         device_property_read_u32(dev, "power-off-delay-us",
 163                                  &pwrseq->power_off_delay_us);
 164
 165         pwrseq->pwrseq.dev = dev;
 166         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 167         pwrseq->pwrseq.owner = THIS_MODULE;
 168         platform_set_drvdata(pdev, pwrseq);
 169
 170         return mmc_pwrseq_register(&pwrseq->pwrseq);
 171 }
 172
 173 static void mmc_pwrseq_simple_remove(struct platform_device *pdev)
 174 {
 175         struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev);
 176
 177         mmc_pwrseq_unregister(&pwrseq->pwrseq);
 178 }
 179
 180 static struct platform_driver mmc_pwrseq_simple_driver = {
 181         .probe = mmc_pwrseq_simple_probe,
 182         .remove = mmc_pwrseq_simple_remove,
 183         .driver = {
 184                 .name = "pwrseq_simple",
 185                 .of_match_table = mmc_pwrseq_simple_of_match,
 186         },
 187 };
 188
 189 module_platform_driver(mmc_pwrseq_simple_driver);
 190 MODULE_DESCRIPTION("Simple power sequence management for MMC");
 191 MODULE_LICENSE("GPL v2");