tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/unicore32/kernel/pwm.c
4 *
5 * Code specific to PKUnity SoC and UniCore ISA
6 *
7 * Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
8 * Copyright (C) 2001-2010 Guan Xuetao
9 */
10
11#include <linux/module.h>
12#include <linux/kernel.h>
13#include <linux/platform_device.h>
14#include <linux/slab.h>
15#include <linux/err.h>
16#include <linux/clk.h>
17#include <linux/io.h>
18#include <linux/pwm.h>
19
20#include <asm/div64.h>
21#include <mach/hardware.h>
22
23struct puv3_pwm_chip {
24 struct pwm_chip chip;
25 void __iomem *base;
26 struct clk *clk;
27};
28
29static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
30{
31 return container_of(chip, struct puv3_pwm_chip, chip);
32}
33
34/*
35 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
36 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
37 */
38static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
39 int duty_ns, int period_ns)
40{
41 unsigned long period_cycles, prescale, pv, dc;
42 struct puv3_pwm_chip *puv3 = to_puv3(chip);
43 unsigned long long c;
44
45 c = clk_get_rate(puv3->clk);
46 c = c * period_ns;
47 do_div(c, 1000000000);
48 period_cycles = c;
49
50 if (period_cycles < 1)
51 period_cycles = 1;
52
53 prescale = (period_cycles - 1) / 1024;
54 pv = period_cycles / (prescale + 1) - 1;
55
56 if (prescale > 63)
57 return -EINVAL;
58
59 if (duty_ns == period_ns)
60 dc = OST_PWMDCCR_FDCYCLE;
61 else
62 dc = (pv + 1) * duty_ns / period_ns;
63
64 /*
65 * NOTE: the clock to PWM has to be enabled first
66 * before writing to the registers
67 */
68 clk_prepare_enable(puv3->clk);
69
70 writel(prescale, puv3->base + OST_PWM_PWCR);
71 writel(pv - dc, puv3->base + OST_PWM_DCCR);
72 writel(pv, puv3->base + OST_PWM_PCR);
73
74 clk_disable_unprepare(puv3->clk);
75
76 return 0;
77}
78
79static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
80{
81 struct puv3_pwm_chip *puv3 = to_puv3(chip);
82
83 return clk_prepare_enable(puv3->clk);
84}
85
86static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
87{
88 struct puv3_pwm_chip *puv3 = to_puv3(chip);
89
90 clk_disable_unprepare(puv3->clk);
91}
92
93static const struct pwm_ops puv3_pwm_ops = {
94 .config = puv3_pwm_config,
95 .enable = puv3_pwm_enable,
96 .disable = puv3_pwm_disable,
97 .owner = THIS_MODULE,
98};
99
100static int pwm_probe(struct platform_device *pdev)
101{
102 struct puv3_pwm_chip *puv3;
103 struct resource *r;
104 int ret;
105
106 puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
107 if (!puv3)
108 return -ENOMEM;
109
110 puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
111 if (IS_ERR(puv3->clk))
112 return PTR_ERR(puv3->clk);
113
114 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
115 puv3->base = devm_ioremap_resource(&pdev->dev, r);
116 if (IS_ERR(puv3->base))
117 return PTR_ERR(puv3->base);
118
119 puv3->chip.dev = &pdev->dev;
120 puv3->chip.ops = &puv3_pwm_ops;
121 puv3->chip.base = -1;
122 puv3->chip.npwm = 1;
123
124 ret = pwmchip_add(&puv3->chip);
125 if (ret < 0) {
126 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
127 return ret;
128 }
129
130 platform_set_drvdata(pdev, puv3);
131 return 0;
132}
133
134static int pwm_remove(struct platform_device *pdev)
135{
136 struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
137
138 return pwmchip_remove(&puv3->chip);
139}
140
141static struct platform_driver puv3_pwm_driver = {
142 .driver = {
143 .name = "PKUnity-v3-PWM",
144 },
145 .probe = pwm_probe,
146 .remove = pwm_remove,
147};
148module_platform_driver(puv3_pwm_driver);
149
150MODULE_LICENSE("GPL v2");