drivers/mmc/core/pwrseq.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  *  MMC power sequence management
   9  */
  10 #include <linux/kernel.h>
  11 #include <linux/err.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14
  15 #include <linux/mmc/host.h>
  16
  17 #include "pwrseq.h"
  18
  19 static DEFINE_MUTEX(pwrseq_list_mutex);
  20 static LIST_HEAD(pwrseq_list);
  21
  22 int mmc_pwrseq_alloc(struct mmc_host *host)
  23 {
  24         struct device_node *np;
  25         struct mmc_pwrseq *p;
  26
  27         np = of_parse_phandle(host->parent->of_node, "mmc-pwrseq", 0);
  28         if (!np)
  29                 return 0;
  30
  31         mutex_lock(&pwrseq_list_mutex);
  32         list_for_each_entry(p, &pwrseq_list, pwrseq_node) {
  33                 if (p->dev->of_node == np) {
  34                         if (!try_module_get(p->owner))
  35                                 dev_err(host->parent,
  36                                         "increasing module refcount failed\n");
  37                         else
  38                                 host->pwrseq = p;
  39
  40                         break;
  41                 }
  42         }
  43
  44         of_node_put(np);
  45         mutex_unlock(&pwrseq_list_mutex);
  46
  47         if (!host->pwrseq)
  48                 return -EPROBE_DEFER;
  49
  50         dev_info(host->parent, "allocated mmc-pwrseq\n");
  51
  52         return 0;
  53 }
  54
  55 void mmc_pwrseq_pre_power_on(struct mmc_host *host)
  56 {
  57         struct mmc_pwrseq *pwrseq = host->pwrseq;
  58
  59         if (pwrseq && pwrseq->ops->pre_power_on)
  60                 pwrseq->ops->pre_power_on(host);
  61 }
  62
  63 void mmc_pwrseq_post_power_on(struct mmc_host *host)
  64 {
  65         struct mmc_pwrseq *pwrseq = host->pwrseq;
  66
  67         if (pwrseq && pwrseq->ops->post_power_on)
  68                 pwrseq->ops->post_power_on(host);
  69 }
  70
  71 void mmc_pwrseq_power_off(struct mmc_host *host)
  72 {
  73         struct mmc_pwrseq *pwrseq = host->pwrseq;
  74
  75         if (pwrseq && pwrseq->ops->power_off)
  76                 pwrseq->ops->power_off(host);
  77 }
  78
  79 void mmc_pwrseq_free(struct mmc_host *host)
  80 {
  81         struct mmc_pwrseq *pwrseq = host->pwrseq;
  82
  83         if (pwrseq) {
  84                 module_put(pwrseq->owner);
  85                 host->pwrseq = NULL;
  86         }
  87 }
  88
  89 int mmc_pwrseq_register(struct mmc_pwrseq *pwrseq)
  90 {
  91         if (!pwrseq || !pwrseq->ops || !pwrseq->dev)
  92                 return -EINVAL;
  93
  94         mutex_lock(&pwrseq_list_mutex);
  95         list_add(&pwrseq->pwrseq_node, &pwrseq_list);
  96         mutex_unlock(&pwrseq_list_mutex);
  97
  98         return 0;
  99 }
 100 EXPORT_SYMBOL_GPL(mmc_pwrseq_register);
 101
 102 void mmc_pwrseq_unregister(struct mmc_pwrseq *pwrseq)
 103 {
 104         if (pwrseq) {
 105                 mutex_lock(&pwrseq_list_mutex);
 106                 list_del(&pwrseq->pwrseq_node);
 107                 mutex_unlock(&pwrseq_list_mutex);
 108         }
 109 }
 110 EXPORT_SYMBOL_GPL(mmc_pwrseq_unregister);