1 /*
2 * Copyright 2012 Freescale Semiconductor, Inc.
3 *
4 * The code contained herein is licensed under the GNU General Public
5 * License. You may obtain a copy of the GNU General Public License
6 * Version 2 or later at the following locations:
7 *
8 * http://www.opensource.org/licenses/gpl-license.html
9 * http://www.gnu.org/copyleft/gpl.html
10 */
11
12 #include <linux/clk.h>
13 #include <linux/err.h>
14 #include <linux/io.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/of_address.h>
19 #include <linux/pinctrl/consumer.h>
20 #include <linux/platform_device.h>
21 #include <linux/pwm.h>
22 #include <linux/slab.h>
23 #include <linux/stmp_device.h>
24
25 #define SET 0x4
26 #define CLR 0x8
27 #define TOG 0xc
28
29 #define PWM_CTRL 0x0
30 #define PWM_ACTIVE0 0x10
31 #define PWM_PERIOD0 0x20
32 #define PERIOD_PERIOD(p) ((p) & 0xffff)
33 #define PERIOD_PERIOD_MAX 0x10000
34 #define PERIOD_ACTIVE_HIGH (3 << 16)
35 #define PERIOD_INACTIVE_LOW (2 << 18)
36 #define PERIOD_CDIV(div) (((div) & 0x7) << 20)
37 #define PERIOD_CDIV_MAX 8
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_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)47 static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
48 int duty_ns, int period_ns)
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
56 rate = clk_get_rate(mxs->clk);
57 while (1) {
58 c = rate / (1 << div);
59 c = c * period_ns;
60 do_div(c, 1000000000);
61 if (c < PERIOD_PERIOD_MAX)
62 break;
63 div++;
64 if (div > PERIOD_CDIV_MAX)
65 return -EINVAL;
66 }
67
68 period_cycles = c;
69 c *= duty_ns;
70 do_div(c, period_ns);
71 duty_cycles = c;
72
73 /*
74 * If the PWM channel is disabled, make sure to turn on the clock
75 * before writing the register. Otherwise, keep it enabled.
76 */
77 if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
78 ret = clk_prepare_enable(mxs->clk);
79 if (ret)
80 return ret;
81 }
82
83 writel(duty_cycles << 16,
84 mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
85 writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
86 PERIOD_INACTIVE_LOW | PERIOD_CDIV(div),
87 mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
88
89 /*
90 * If the PWM is not enabled, turn the clock off again to save power.
91 */
92 if (!test_bit(PWMF_ENABLED, &pwm->flags))
93 clk_disable_unprepare(mxs->clk);
94
95 return 0;
96 }
97
mxs_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)98 static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
99 {
100 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
101 int ret;
102
103 ret = clk_prepare_enable(mxs->clk);
104 if (ret)
105 return ret;
106
107 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
108
109 return 0;
110 }
111
mxs_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)112 static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
113 {
114 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
115
116 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
117
118 clk_disable_unprepare(mxs->clk);
119 }
120
121 static const struct pwm_ops mxs_pwm_ops = {
122 .config = mxs_pwm_config,
123 .enable = mxs_pwm_enable,
124 .disable = mxs_pwm_disable,
125 .owner = THIS_MODULE,
126 };
127
mxs_pwm_probe(struct platform_device * pdev)128 static int mxs_pwm_probe(struct platform_device *pdev)
129 {
130 struct device_node *np = pdev->dev.of_node;
131 struct mxs_pwm_chip *mxs;
132 struct resource *res;
133 struct pinctrl *pinctrl;
134 int ret;
135
136 mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
137 if (!mxs)
138 return -ENOMEM;
139
140 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
141 mxs->base = devm_ioremap_resource(&pdev->dev, res);
142 if (IS_ERR(mxs->base))
143 return PTR_ERR(mxs->base);
144
145 pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
146 if (IS_ERR(pinctrl))
147 return PTR_ERR(pinctrl);
148
149 mxs->clk = devm_clk_get(&pdev->dev, NULL);
150 if (IS_ERR(mxs->clk))
151 return PTR_ERR(mxs->clk);
152
153 mxs->chip.dev = &pdev->dev;
154 mxs->chip.ops = &mxs_pwm_ops;
155 mxs->chip.base = -1;
156 ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
157 if (ret < 0) {
158 dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
159 return ret;
160 }
161
162 ret = pwmchip_add(&mxs->chip);
163 if (ret < 0) {
164 dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
165 return ret;
166 }
167
168 platform_set_drvdata(pdev, mxs);
169
170 stmp_reset_block(mxs->base);
171
172 return 0;
173 }
174
mxs_pwm_remove(struct platform_device * pdev)175 static int mxs_pwm_remove(struct platform_device *pdev)
176 {
177 struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev);
178
179 return pwmchip_remove(&mxs->chip);
180 }
181
182 static const struct of_device_id mxs_pwm_dt_ids[] = {
183 { .compatible = "fsl,imx23-pwm", },
184 { /* sentinel */ }
185 };
186 MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
187
188 static struct platform_driver mxs_pwm_driver = {
189 .driver = {
190 .name = "mxs-pwm",
191 .of_match_table = of_match_ptr(mxs_pwm_dt_ids),
192 },
193 .probe = mxs_pwm_probe,
194 .remove = mxs_pwm_remove,
195 };
196 module_platform_driver(mxs_pwm_driver);
197
198 MODULE_ALIAS("platform:mxs-pwm");
199 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
200 MODULE_DESCRIPTION("Freescale MXS PWM Driver");
201 MODULE_LICENSE("GPL v2");
202