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190 lines · 5.1 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2014 Linaro Ltd
4 *
5 * Author: Ulf Hansson <[email protected]>
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
27struct 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
39static 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
63static 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
79static 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
92static 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
111static 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
117static const struct of_device_id mmc_pwrseq_simple_of_match[] = {
118 { .compatible = "mmc-pwrseq-simple",},
119 {/* sentinel */},
120};
121MODULE_DEVICE_TABLE(of, mmc_pwrseq_simple_of_match);
122
123static 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
172static 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
179static 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
188module_platform_driver(mmc_pwrseq_simple_driver);
189MODULE_DESCRIPTION("Simple power sequence management for MMC");
190MODULE_LICENSE("GPL v2");