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