1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright 2012 Freescale Semiconductor, Inc.
4 */
5
6 #include <linux/clk.h>
7 #include <linux/err.h>
8 #include <linux/io.h>
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/of.h>
12 #include <linux/platform_device.h>
13 #include <linux/pwm.h>
14 #include <linux/slab.h>
15 #include <linux/stmp_device.h>
16
17 #define SET 0x4
18 #define CLR 0x8
19 #define TOG 0xc
20
21 #define PWM_CTRL 0x0
22 #define PWM_ACTIVE0 0x10
23 #define PWM_PERIOD0 0x20
24 #define PERIOD_PERIOD(p) ((p) & 0xffff)
25 #define PERIOD_PERIOD_MAX 0x10000
26 #define PERIOD_ACTIVE_HIGH (3 << 16)
27 #define PERIOD_ACTIVE_LOW (2 << 16)
28 #define PERIOD_INACTIVE_HIGH (3 << 18)
29 #define PERIOD_INACTIVE_LOW (2 << 18)
30 #define PERIOD_POLARITY_NORMAL (PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW)
31 #define PERIOD_POLARITY_INVERSE (PERIOD_ACTIVE_LOW | PERIOD_INACTIVE_HIGH)
32 #define PERIOD_CDIV(div) (((div) & 0x7) << 20)
33 #define PERIOD_CDIV_MAX 8
34
35 static const u8 cdiv_shift[PERIOD_CDIV_MAX] = {
36 0, 1, 2, 3, 4, 6, 8, 10
37 };
38
39 struct mxs_pwm_chip {
40 struct pwm_chip chip;
41 struct clk *clk;
42 void __iomem *base;
43 };
44
45 #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
46
mxs_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)47 static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
48 const struct pwm_state *state)
49 {
50 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
51 int ret, div = 0;
52 unsigned int period_cycles, duty_cycles;
53 unsigned long rate;
54 unsigned long long c;
55 unsigned int pol_bits;
56
57 /*
58 * If the PWM channel is disabled, make sure to turn on the
59 * clock before calling clk_get_rate() and writing to the
60 * registers. Otherwise, just keep it enabled.
61 */
62 if (!pwm_is_enabled(pwm)) {
63 ret = clk_prepare_enable(mxs->clk);
64 if (ret)
65 return ret;
66 }
67
68 if (!state->enabled && pwm_is_enabled(pwm))
69 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
70
71 rate = clk_get_rate(mxs->clk);
72 while (1) {
73 c = rate >> cdiv_shift[div];
74 c = c * state->period;
75 do_div(c, 1000000000);
76 if (c < PERIOD_PERIOD_MAX)
77 break;
78 div++;
79 if (div >= PERIOD_CDIV_MAX)
80 return -EINVAL;
81 }
82
83 period_cycles = c;
84 c *= state->duty_cycle;
85 do_div(c, state->period);
86 duty_cycles = c;
87
88 /*
89 * The data sheet the says registers must be written to in
90 * this order (ACTIVEn, then PERIODn). Also, the new settings
91 * only take effect at the beginning of a new period, avoiding
92 * glitches.
93 */
94
95 pol_bits = state->polarity == PWM_POLARITY_NORMAL ?
96 PERIOD_POLARITY_NORMAL : PERIOD_POLARITY_INVERSE;
97 writel(duty_cycles << 16,
98 mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
99 writel(PERIOD_PERIOD(period_cycles) | pol_bits | PERIOD_CDIV(div),
100 mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
101
102 if (state->enabled) {
103 if (!pwm_is_enabled(pwm)) {
104 /*
105 * The clock was enabled above. Just enable
106 * the channel in the control register.
107 */
108 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
109 }
110 } else {
111 clk_disable_unprepare(mxs->clk);
112 }
113 return 0;
114 }
115
116 static const struct pwm_ops mxs_pwm_ops = {
117 .apply = mxs_pwm_apply,
118 .owner = THIS_MODULE,
119 };
120
mxs_pwm_probe(struct platform_device * pdev)121 static int mxs_pwm_probe(struct platform_device *pdev)
122 {
123 struct device_node *np = pdev->dev.of_node;
124 struct mxs_pwm_chip *mxs;
125 int ret;
126
127 mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
128 if (!mxs)
129 return -ENOMEM;
130
131 mxs->base = devm_platform_ioremap_resource(pdev, 0);
132 if (IS_ERR(mxs->base))
133 return PTR_ERR(mxs->base);
134
135 mxs->clk = devm_clk_get(&pdev->dev, NULL);
136 if (IS_ERR(mxs->clk))
137 return PTR_ERR(mxs->clk);
138
139 mxs->chip.dev = &pdev->dev;
140 mxs->chip.ops = &mxs_pwm_ops;
141 mxs->chip.of_xlate = of_pwm_xlate_with_flags;
142 mxs->chip.of_pwm_n_cells = 3;
143
144 ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
145 if (ret < 0) {
146 dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
147 return ret;
148 }
149
150 ret = pwmchip_add(&mxs->chip);
151 if (ret < 0) {
152 dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
153 return ret;
154 }
155
156 platform_set_drvdata(pdev, mxs);
157
158 ret = stmp_reset_block(mxs->base);
159 if (ret)
160 goto pwm_remove;
161
162 return 0;
163
164 pwm_remove:
165 pwmchip_remove(&mxs->chip);
166 return ret;
167 }
168
mxs_pwm_remove(struct platform_device * pdev)169 static int mxs_pwm_remove(struct platform_device *pdev)
170 {
171 struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev);
172
173 return pwmchip_remove(&mxs->chip);
174 }
175
176 static const struct of_device_id mxs_pwm_dt_ids[] = {
177 { .compatible = "fsl,imx23-pwm", },
178 { /* sentinel */ }
179 };
180 MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
181
182 static struct platform_driver mxs_pwm_driver = {
183 .driver = {
184 .name = "mxs-pwm",
185 .of_match_table = mxs_pwm_dt_ids,
186 },
187 .probe = mxs_pwm_probe,
188 .remove = mxs_pwm_remove,
189 };
190 module_platform_driver(mxs_pwm_driver);
191
192 MODULE_ALIAS("platform:mxs-pwm");
193 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
194 MODULE_DESCRIPTION("Freescale MXS PWM Driver");
195 MODULE_LICENSE("GPL v2");
196