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_multi_set_value_cansleep(reset_gpios, values); 58 59 bitmap_free(values); 60 } 61 } 62 63 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host) 64 { 65 struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq); 66 67 if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) { 68 clk_prepare_enable(pwrseq->ext_clk); 69 pwrseq->clk_enabled = true; 70 } 71 72 if (pwrseq->reset_ctrl) { 73 reset_control_deassert(pwrseq->reset_ctrl); 74 reset_control_assert(pwrseq->reset_ctrl); 75 } else 76 mmc_pwrseq_simple_set_gpios_value(pwrseq, 1); 77 } 78 79 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host) 80 { 81 struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq); 82 83 if (pwrseq->reset_ctrl) 84 reset_control_deassert(pwrseq->reset_ctrl); 85 else 86 mmc_pwrseq_simple_set_gpios_value(pwrseq, 0); 87 88 if (pwrseq->post_power_on_delay_ms) 89 msleep(pwrseq->post_power_on_delay_ms); 90 } 91 92 static void mmc_pwrseq_simple_power_off(struct mmc_host *host) 93 { 94 struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq); 95 96 if (pwrseq->reset_ctrl) 97 reset_control_assert(pwrseq->reset_ctrl); 98 else 99 mmc_pwrseq_simple_set_gpios_value(pwrseq, 1); 100 101 if (pwrseq->power_off_delay_us) 102 usleep_range(pwrseq->power_off_delay_us, 103 2 * pwrseq->power_off_delay_us); 104 105 if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) { 106 clk_disable_unprepare(pwrseq->ext_clk); 107 pwrseq->clk_enabled = false; 108 } 109 } 110 111 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = { 112 .pre_power_on = mmc_pwrseq_simple_pre_power_on, 113 .post_power_on = mmc_pwrseq_simple_post_power_on, 114 .power_off = mmc_pwrseq_simple_power_off, 115 }; 116 117 static const struct of_device_id mmc_pwrseq_simple_of_match[] = { 118 { .compatible = "mmc-pwrseq-simple",}, 119 {/* sentinel */}, 120 }; 121 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match); 122 123 static int mmc_pwrseq_simple_probe(struct platform_device *pdev) 124 { 125 struct mmc_pwrseq_simple *pwrseq; 126 struct device *dev = &pdev->dev; 127 int ngpio; 128 129 pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL); 130 if (!pwrseq) 131 return -ENOMEM; 132 133 pwrseq->ext_clk = devm_clk_get(dev, "ext_clock"); 134 if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT) 135 return dev_err_probe(dev, PTR_ERR(pwrseq->ext_clk), "external clock not ready\n"); 136 137 ngpio = of_count_phandle_with_args(dev->of_node, "reset-gpios", "#gpio-cells"); 138 if (ngpio == 1) { 139 pwrseq->reset_ctrl = devm_reset_control_get_optional_shared(dev, NULL); 140 if (IS_ERR(pwrseq->reset_ctrl)) 141 return dev_err_probe(dev, PTR_ERR(pwrseq->reset_ctrl), 142 "reset control not ready\n"); 143 } 144 145 /* 146 * Fallback to GPIO based reset control in case of multiple reset lines 147 * are specified or the platform doesn't have support for RESET at all. 148 */ 149 if (!pwrseq->reset_ctrl) { 150 pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset", GPIOD_OUT_HIGH); 151 if (IS_ERR(pwrseq->reset_gpios) && 152 PTR_ERR(pwrseq->reset_gpios) != -ENOENT && 153 PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) { 154 return dev_err_probe(dev, PTR_ERR(pwrseq->reset_gpios), 155 "reset GPIOs not ready\n"); 156 } 157 } 158 159 device_property_read_u32(dev, "post-power-on-delay-ms", 160 &pwrseq->post_power_on_delay_ms); 161 device_property_read_u32(dev, "power-off-delay-us", 162 &pwrseq->power_off_delay_us); 163 164 pwrseq->pwrseq.dev = dev; 165 pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops; 166 pwrseq->pwrseq.owner = THIS_MODULE; 167 platform_set_drvdata(pdev, pwrseq); 168 169 return mmc_pwrseq_register(&pwrseq->pwrseq); 170 } 171 172 static void mmc_pwrseq_simple_remove(struct platform_device *pdev) 173 { 174 struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev); 175 176 mmc_pwrseq_unregister(&pwrseq->pwrseq); 177 } 178 179 static struct platform_driver mmc_pwrseq_simple_driver = { 180 .probe = mmc_pwrseq_simple_probe, 181 .remove = mmc_pwrseq_simple_remove, 182 .driver = { 183 .name = "pwrseq_simple", 184 .of_match_table = mmc_pwrseq_simple_of_match, 185 }, 186 }; 187 188 module_platform_driver(mmc_pwrseq_simple_driver); 189 MODULE_DESCRIPTION("Simple power sequence management for MMC"); 190 MODULE_LICENSE("GPL v2"); 191