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/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/device.h>
  14 #include <linux/err.h>
  15 #include <linux/gpio/consumer.h>
  16
  17 #include <linux/mmc/host.h>
  18
  19 #include "pwrseq.h"
  20
  21 struct mmc_pwrseq_simple {
  22         struct mmc_pwrseq pwrseq;
  23         bool clk_enabled;
  24         struct clk *ext_clk;
  25         struct gpio_descs *reset_gpios;
  26 };
  27
  28 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
  29                                               int value)
  30 {
  31         struct gpio_descs *reset_gpios = pwrseq->reset_gpios;
  32
  33         if (!IS_ERR(reset_gpios)) {
  34                 int i;
  35                 int values[reset_gpios->ndescs];
  36
  37                 for (i = 0; i < reset_gpios->ndescs; i++)
  38                         values[i] = value;
  39
  40                 gpiod_set_array_value_cansleep(
  41                         reset_gpios->ndescs, reset_gpios->desc, values);
  42         }
  43 }
  44
  45 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
  46 {
  47         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  48                                         struct mmc_pwrseq_simple, pwrseq);
  49
  50         if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
  51                 clk_prepare_enable(pwrseq->ext_clk);
  52                 pwrseq->clk_enabled = true;
  53         }
  54
  55         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  56 }
  57
  58 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
  59 {
  60         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  61                                         struct mmc_pwrseq_simple, pwrseq);
  62
  63         mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
  64 }
  65
  66 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
  67 {
  68         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  69                                         struct mmc_pwrseq_simple, pwrseq);
  70
  71         mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
  72
  73         if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
  74                 clk_disable_unprepare(pwrseq->ext_clk);
  75                 pwrseq->clk_enabled = false;
  76         }
  77 }
  78
  79 static void mmc_pwrseq_simple_free(struct mmc_host *host)
  80 {
  81         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
  82                                         struct mmc_pwrseq_simple, pwrseq);
  83
  84         if (!IS_ERR(pwrseq->reset_gpios))
  85                 gpiod_put_array(pwrseq->reset_gpios);
  86
  87         if (!IS_ERR(pwrseq->ext_clk))
  88                 clk_put(pwrseq->ext_clk);
  89
  90         kfree(pwrseq);
  91 }
  92
  93 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
  94         .pre_power_on = mmc_pwrseq_simple_pre_power_on,
  95         .post_power_on = mmc_pwrseq_simple_post_power_on,
  96         .power_off = mmc_pwrseq_simple_power_off,
  97         .free = mmc_pwrseq_simple_free,
  98 };
  99
 100 struct mmc_pwrseq *mmc_pwrseq_simple_alloc(struct mmc_host *host,
 101                                            struct device *dev)
 102 {
 103         struct mmc_pwrseq_simple *pwrseq;
 104         int ret = 0;
 105
 106         pwrseq = kzalloc(sizeof(*pwrseq), GFP_KERNEL);
 107         if (!pwrseq)
 108                 return ERR_PTR(-ENOMEM);
 109
 110         pwrseq->ext_clk = clk_get(dev, "ext_clock");
 111         if (IS_ERR(pwrseq->ext_clk) &&
 112             PTR_ERR(pwrseq->ext_clk) != -ENOENT) {
 113                 ret = PTR_ERR(pwrseq->ext_clk);
 114                 goto free;
 115         }
 116
 117         pwrseq->reset_gpios = gpiod_get_array(dev, "reset", GPIOD_OUT_HIGH);
 118         if (IS_ERR(pwrseq->reset_gpios) &&
 119             PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
 120             PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
 121                 ret = PTR_ERR(pwrseq->reset_gpios);
 122                 goto clk_put;
 123         }
 124
 125         pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 126
 127         return &pwrseq->pwrseq;
 128 clk_put:
 129         if (!IS_ERR(pwrseq->ext_clk))
 130                 clk_put(pwrseq->ext_clk);
 131 free:
 132         kfree(pwrseq);
 133         return ERR_PTR(ret);
 134 }