1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
// SPDX-License-Identifier: GPL-2.0
/*
* simple driver for PWM (Pulse Width Modulator) controller
*
* Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
*/
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#define MX1_PWMC 0x00 /* PWM Control Register */
#define MX1_PWMS 0x04 /* PWM Sample Register */
#define MX1_PWMP 0x08 /* PWM Period Register */
#define MX1_PWMC_EN BIT(4)
struct pwm_imx1_chip {
struct clk *clk_ipg;
struct clk *clk_per;
void __iomem *mmio_base;
struct pwm_chip chip;
};
#define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip)
static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip)
{
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
int ret;
ret = clk_prepare_enable(imx->clk_ipg);
if (ret)
return ret;
ret = clk_prepare_enable(imx->clk_per);
if (ret) {
clk_disable_unprepare(imx->clk_ipg);
return ret;
}
return 0;
}
static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip)
{
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
clk_disable_unprepare(imx->clk_per);
clk_disable_unprepare(imx->clk_ipg);
}
static int pwm_imx1_config(struct pwm_chip *chip,
struct pwm_device *pwm, u64 duty_ns, u64 period_ns)
{
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
u32 max, p;
/*
* The PWM subsystem allows for exact frequencies. However,
* I cannot connect a scope on my device to the PWM line and
* thus cannot provide the program the PWM controller
* exactly. Instead, I'm relying on the fact that the
* Bootloader (u-boot or WinCE+haret) has programmed the PWM
* function group already. So I'll just modify the PWM sample
* register to follow the ratio of duty_ns vs. period_ns
* accordingly.
*
* This is good enough for programming the brightness of
* the LCD backlight.
*
* The real implementation would divide PERCLK[0] first by
* both the prescaler (/1 .. /128) and then by CLKSEL
* (/2 .. /16).
*/
max = readl(imx->mmio_base + MX1_PWMP);
p = mul_u64_u64_div_u64(max, duty_ns, period_ns);
writel(max - p, imx->mmio_base + MX1_PWMS);
return 0;
}
static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
u32 value;
int ret;
ret = pwm_imx1_clk_prepare_enable(chip);
if (ret < 0)
return ret;
value = readl(imx->mmio_base + MX1_PWMC);
value |= MX1_PWMC_EN;
writel(value, imx->mmio_base + MX1_PWMC);
return 0;
}
static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
u32 value;
value = readl(imx->mmio_base + MX1_PWMC);
value &= ~MX1_PWMC_EN;
writel(value, imx->mmio_base + MX1_PWMC);
pwm_imx1_clk_disable_unprepare(chip);
}
static int pwm_imx1_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
int err;
if (state->polarity != PWM_POLARITY_NORMAL)
return -EINVAL;
if (!state->enabled) {
if (pwm->state.enabled)
pwm_imx1_disable(chip, pwm);
return 0;
}
err = pwm_imx1_config(chip, pwm, state->duty_cycle, state->period);
if (err)
return err;
if (!pwm->state.enabled)
return pwm_imx1_enable(chip, pwm);
return 0;
}
static const struct pwm_ops pwm_imx1_ops = {
.apply = pwm_imx1_apply,
.owner = THIS_MODULE,
};
static const struct of_device_id pwm_imx1_dt_ids[] = {
{ .compatible = "fsl,imx1-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids);
static int pwm_imx1_probe(struct platform_device *pdev)
{
struct pwm_imx1_chip *imx;
imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
if (!imx)
return -ENOMEM;
imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
if (IS_ERR(imx->clk_ipg))
return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_ipg),
"getting ipg clock failed\n");
imx->clk_per = devm_clk_get(&pdev->dev, "per");
if (IS_ERR(imx->clk_per))
return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per),
"failed to get peripheral clock\n");
imx->chip.ops = &pwm_imx1_ops;
imx->chip.dev = &pdev->dev;
imx->chip.npwm = 1;
imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(imx->mmio_base))
return PTR_ERR(imx->mmio_base);
return devm_pwmchip_add(&pdev->dev, &imx->chip);
}
static struct platform_driver pwm_imx1_driver = {
.driver = {
.name = "pwm-imx1",
.of_match_table = pwm_imx1_dt_ids,
},
.probe = pwm_imx1_probe,
};
module_platform_driver(pwm_imx1_driver);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
|
