xref: /linux/drivers/mmc/core/pwrseq_simple.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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 
21 #include <linux/mmc/host.h>
22 
23 #include "pwrseq.h"
24 
25 struct mmc_pwrseq_simple {
26 	struct mmc_pwrseq pwrseq;
27 	bool clk_enabled;
28 	u32 post_power_on_delay_ms;
29 	u32 power_off_delay_us;
30 	struct clk *ext_clk;
31 	struct gpio_descs *reset_gpios;
32 };
33 
34 #define to_pwrseq_simple(p) container_of(p, struct mmc_pwrseq_simple, pwrseq)
35 
mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple * pwrseq,int value)36 static void mmc_pwrseq_simple_set_gpios_value(struct mmc_pwrseq_simple *pwrseq,
37 					      int value)
38 {
39 	struct gpio_descs *reset_gpios = pwrseq->reset_gpios;
40 
41 	if (!IS_ERR(reset_gpios)) {
42 		unsigned long *values;
43 		int nvalues = reset_gpios->ndescs;
44 
45 		values = bitmap_alloc(nvalues, GFP_KERNEL);
46 		if (!values)
47 			return;
48 
49 		if (value)
50 			bitmap_fill(values, nvalues);
51 		else
52 			bitmap_zero(values, nvalues);
53 
54 		gpiod_set_array_value_cansleep(nvalues, reset_gpios->desc,
55 					       reset_gpios->info, values);
56 
57 		bitmap_free(values);
58 	}
59 }
60 
mmc_pwrseq_simple_pre_power_on(struct mmc_host * host)61 static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
62 {
63 	struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
64 
65 	if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
66 		clk_prepare_enable(pwrseq->ext_clk);
67 		pwrseq->clk_enabled = true;
68 	}
69 
70 	mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
71 }
72 
mmc_pwrseq_simple_post_power_on(struct mmc_host * host)73 static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
74 {
75 	struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
76 
77 	mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
78 
79 	if (pwrseq->post_power_on_delay_ms)
80 		msleep(pwrseq->post_power_on_delay_ms);
81 }
82 
mmc_pwrseq_simple_power_off(struct mmc_host * host)83 static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
84 {
85 	struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
86 
87 	mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
88 
89 	if (pwrseq->power_off_delay_us)
90 		usleep_range(pwrseq->power_off_delay_us,
91 			2 * pwrseq->power_off_delay_us);
92 
93 	if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
94 		clk_disable_unprepare(pwrseq->ext_clk);
95 		pwrseq->clk_enabled = false;
96 	}
97 }
98 
99 static const struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
100 	.pre_power_on = mmc_pwrseq_simple_pre_power_on,
101 	.post_power_on = mmc_pwrseq_simple_post_power_on,
102 	.power_off = mmc_pwrseq_simple_power_off,
103 };
104 
105 static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
106 	{ .compatible = "mmc-pwrseq-simple",},
107 	{/* sentinel */},
108 };
109 MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
110 
mmc_pwrseq_simple_probe(struct platform_device * pdev)111 static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
112 {
113 	struct mmc_pwrseq_simple *pwrseq;
114 	struct device *dev = &pdev->dev;
115 
116 	pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
117 	if (!pwrseq)
118 		return -ENOMEM;
119 
120 	pwrseq->ext_clk = devm_clk_get(dev, "ext_clock");
121 	if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
122 		return dev_err_probe(dev, PTR_ERR(pwrseq->ext_clk), "external clock not ready\n");
123 
124 	pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset",
125 							GPIOD_OUT_HIGH);
126 	if (IS_ERR(pwrseq->reset_gpios) &&
127 	    PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
128 	    PTR_ERR(pwrseq->reset_gpios) != -ENOSYS) {
129 		return dev_err_probe(dev, PTR_ERR(pwrseq->reset_gpios), "reset GPIOs not ready\n");
130 	}
131 
132 	device_property_read_u32(dev, "post-power-on-delay-ms",
133 				 &pwrseq->post_power_on_delay_ms);
134 	device_property_read_u32(dev, "power-off-delay-us",
135 				 &pwrseq->power_off_delay_us);
136 
137 	pwrseq->pwrseq.dev = dev;
138 	pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
139 	pwrseq->pwrseq.owner = THIS_MODULE;
140 	platform_set_drvdata(pdev, pwrseq);
141 
142 	return mmc_pwrseq_register(&pwrseq->pwrseq);
143 }
144 
mmc_pwrseq_simple_remove(struct platform_device * pdev)145 static void mmc_pwrseq_simple_remove(struct platform_device *pdev)
146 {
147 	struct mmc_pwrseq_simple *pwrseq = platform_get_drvdata(pdev);
148 
149 	mmc_pwrseq_unregister(&pwrseq->pwrseq);
150 }
151 
152 static struct platform_driver mmc_pwrseq_simple_driver = {
153 	.probe = mmc_pwrseq_simple_probe,
154 	.remove_new = mmc_pwrseq_simple_remove,
155 	.driver = {
156 		.name = "pwrseq_simple",
157 		.of_match_table = mmc_pwrseq_simple_of_match,
158 	},
159 };
160 
161 module_platform_driver(mmc_pwrseq_simple_driver);
162 MODULE_DESCRIPTION("Simple power sequence management for MMC");
163 MODULE_LICENSE("GPL v2");
164