mmc/core/pwrseq_simple.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *  Copyright (C) 2014 Linaro Ltd
0004  *
0005  * Author: Ulf Hansson <ulf.hansson@linaro.org>
0006  *
0007  *  Simple MMC power sequence management
0008  */
0009 #include <linux/clk.h>
0010 #include <linux/init.h>
0011 #include <linux/kernel.h>
0012 #include <linux/platform_device.h>
0013 #include <linux/module.h>
0014 #include <linux/slab.h>
0015 #include <linux/device.h>
0016 #include <linux/err.h>
0017 #include <linux/gpio/consumer.h>
0018 #include <linux/delay.h>
0019 #include <linux/property.h>
0020
0021 #include <linux/mmc/host.h>
0022
0023 #include "pwrseq.h"
0024
0025 struct mmc_pwrseq_simple {
0026     struct mmc_pwrseq pwrseq;
0027     bool clk_enabled;
0028     u32 post_power_on_delay_ms;
0029     u32 power_off_delay_us;
0030     struct clk *ext_clk;
0031     struct gpio_descs *reset_gpios;
0032 };
0033
0034 #define to_pwrseq_simple(p) container_of(p, struct mmc_pwrseq_simple, pwrseq)
0035
0036 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
0037                           int value)
0038 {
0039     struct gpio_descs *reset_gpios = pwrseq->reset_gpios;
0040
0041     if (!IS_ERR(reset_gpios)) {
0042         unsigned long *values;
0043         int nvalues = reset_gpios->ndescs;
0044
0045         values = bitmap_alloc(nvalues, GFP_KERNEL);
0046         if (!values)
0047             return;
0048
0049         if (value)
0050             bitmap_fill(values, nvalues);
0051         else
0052             bitmap_zero(values, nvalues);
0053
0054         gpiod_set_array_value_cansleep(nvalues, reset_gpios->desc,
0055                            reset_gpios->info, values);
0056
0057         bitmap_free(values);
0058     }
0059 }
0060
0061 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
0062 {
0063     struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
0064
0065     if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
0066         clk_prepare_enable(pwrseq->ext_clk);
0067         pwrseq->clk_enabled = true;
0068     }
0069
0070     mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
0071 }
0072
0073 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
0074 {
0075     struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
0076
0077     mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
0078
0079     if (pwrseq->post_power_on_delay_ms)
0080         msleep(pwrseq->post_power_on_delay_ms);
0081 }
0082
0083 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
0084 {
0085     struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
0086
0087     mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
0088
0089     if (pwrseq->power_off_delay_us)
0090         usleep_range(pwrseq->power_off_delay_us,
0091             2 * pwrseq->power_off_delay_us);
0092
0093     if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
0094         clk_disable_unprepare(pwrseq->ext_clk);
0095         pwrseq->clk_enabled = false;
0096     }
0097 }
0098
0099 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
0100     .pre_power_on = mmc_pwrseq_simple_pre_power_on,
0101     .post_power_on = mmc_pwrseq_simple_post_power_on,
0102     .power_off = mmc_pwrseq_simple_power_off,
0103 };
0104
0105 static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
0106     { .compatible = "mmc-pwrseq-simple",},
0107     {/* sentinel */},
0108 };
0109 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
0110
0111 static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
0112 {
0113     struct mmc_pwrseq_simple *pwrseq;
0114     struct device *dev = &pdev->dev;
0115
0116     pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
0117     if (!pwrseq)
0118         return -ENOMEM;
0119
0120     pwrseq->ext_clk = devm_clk_get(dev, "ext_clock");
0121     if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
0122         return PTR_ERR(pwrseq->ext_clk);
0123
0124     pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset",
0125                             GPIOD_OUT_HIGH);
0126     if (IS_ERR(pwrseq->reset_gpios) &&
0127         PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
0128         PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
0129         return PTR_ERR(pwrseq->reset_gpios);
0130     }
0131
0132     device_property_read_u32(dev, "post-power-on-delay-ms",
0133                  &pwrseq->post_power_on_delay_ms);
0134     device_property_read_u32(dev, "power-off-delay-us",
0135                  &pwrseq->power_off_delay_us);
0136
0137     pwrseq->pwrseq.dev = dev;
0138     pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
0139     pwrseq->pwrseq.owner = THIS_MODULE;
0140     platform_set_drvdata(pdev, pwrseq);
0141
0142     return mmc_pwrseq_register(&pwrseq->pwrseq);
0143 }
0144
0145 static int mmc_pwrseq_simple_remove(struct platform_device *pdev)
0146 {
0147     struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev);
0148
0149     mmc_pwrseq_unregister(&pwrseq->pwrseq);
0150
0151     return 0;
0152 }
0153
0154 static struct platform_driver mmc_pwrseq_simple_driver = {
0155     .probe = mmc_pwrseq_simple_probe,
0156     .remove = mmc_pwrseq_simple_remove,
0157     .driver = {
0158         .name = "pwrseq_simple",
0159         .of_match_table = mmc_pwrseq_simple_of_match,
0160     },
0161 };
0162
0163 module_platform_driver(mmc_pwrseq_simple_driver);
0164 MODULE_LICENSE("GPL v2");