1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * drivers/pwm/pwm-pxa.c
4  *
5  * simple driver for PWM (Pulse Width Modulator) controller
6  *
7  * 2008-02-13	initial version
8  *		eric miao <eric.miao@marvell.com>
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 #include <linux/of_device.h>
20 
21 #include <asm/div64.h>
22 
23 #define HAS_SECONDARY_PWM	0x10
24 
25 static const struct platform_device_id pwm_id_table[] = {
26 	/*   PWM    has_secondary_pwm? */
27 	{ "pxa25x-pwm", 0 },
28 	{ "pxa27x-pwm", HAS_SECONDARY_PWM },
29 	{ "pxa168-pwm", 0 },
30 	{ "pxa910-pwm", 0 },
31 	{ },
32 };
33 MODULE_DEVICE_TABLE(platform, pwm_id_table);
34 
35 /* PWM registers and bits definitions */
36 #define PWMCR		(0x00)
37 #define PWMDCR		(0x04)
38 #define PWMPCR		(0x08)
39 
40 #define PWMCR_SD	(1 << 6)
41 #define PWMDCR_FD	(1 << 10)
42 
43 struct pxa_pwm_chip {
44 	struct pwm_chip	chip;
45 	struct device	*dev;
46 
47 	struct clk	*clk;
48 	void __iomem	*mmio_base;
49 };
50 
to_pxa_pwm_chip(struct pwm_chip * chip)51 static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
52 {
53 	return container_of(chip, struct pxa_pwm_chip, chip);
54 }
55 
56 /*
57  * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
58  * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
59  */
pxa_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)60 static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
61 			  int duty_ns, int period_ns)
62 {
63 	struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
64 	unsigned long long c;
65 	unsigned long period_cycles, prescale, pv, dc;
66 	unsigned long offset;
67 	int rc;
68 
69 	offset = pwm->hwpwm ? 0x10 : 0;
70 
71 	c = clk_get_rate(pc->clk);
72 	c = c * period_ns;
73 	do_div(c, 1000000000);
74 	period_cycles = c;
75 
76 	if (period_cycles < 1)
77 		period_cycles = 1;
78 	prescale = (period_cycles - 1) / 1024;
79 	pv = period_cycles / (prescale + 1) - 1;
80 
81 	if (prescale > 63)
82 		return -EINVAL;
83 
84 	if (duty_ns == period_ns)
85 		dc = PWMDCR_FD;
86 	else
87 		dc = (pv + 1) * duty_ns / period_ns;
88 
89 	/* NOTE: the clock to PWM has to be enabled first
90 	 * before writing to the registers
91 	 */
92 	rc = clk_prepare_enable(pc->clk);
93 	if (rc < 0)
94 		return rc;
95 
96 	writel(prescale, pc->mmio_base + offset + PWMCR);
97 	writel(dc, pc->mmio_base + offset + PWMDCR);
98 	writel(pv, pc->mmio_base + offset + PWMPCR);
99 
100 	clk_disable_unprepare(pc->clk);
101 	return 0;
102 }
103 
pxa_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)104 static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
105 {
106 	struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
107 
108 	return clk_prepare_enable(pc->clk);
109 }
110 
pxa_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)111 static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
112 {
113 	struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
114 
115 	clk_disable_unprepare(pc->clk);
116 }
117 
118 static const struct pwm_ops pxa_pwm_ops = {
119 	.config = pxa_pwm_config,
120 	.enable = pxa_pwm_enable,
121 	.disable = pxa_pwm_disable,
122 	.owner = THIS_MODULE,
123 };
124 
125 #ifdef CONFIG_OF
126 /*
127  * Device tree users must create one device instance for each PWM channel.
128  * Hence we dispense with the HAS_SECONDARY_PWM and "tell" the original driver
129  * code that this is a single channel pxa25x-pwm.  Currently all devices are
130  * supported identically.
131  */
132 static const struct of_device_id pwm_of_match[] = {
133 	{ .compatible = "marvell,pxa250-pwm", .data = &pwm_id_table[0]},
134 	{ .compatible = "marvell,pxa270-pwm", .data = &pwm_id_table[0]},
135 	{ .compatible = "marvell,pxa168-pwm", .data = &pwm_id_table[0]},
136 	{ .compatible = "marvell,pxa910-pwm", .data = &pwm_id_table[0]},
137 	{ }
138 };
139 MODULE_DEVICE_TABLE(of, pwm_of_match);
140 #else
141 #define pwm_of_match NULL
142 #endif
143 
pxa_pwm_get_id_dt(struct device * dev)144 static const struct platform_device_id *pxa_pwm_get_id_dt(struct device *dev)
145 {
146 	const struct of_device_id *id = of_match_device(pwm_of_match, dev);
147 
148 	return id ? id->data : NULL;
149 }
150 
151 static struct pwm_device *
pxa_pwm_of_xlate(struct pwm_chip * pc,const struct of_phandle_args * args)152 pxa_pwm_of_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
153 {
154 	struct pwm_device *pwm;
155 
156 	pwm = pwm_request_from_chip(pc, 0, NULL);
157 	if (IS_ERR(pwm))
158 		return pwm;
159 
160 	pwm->args.period = args->args[0];
161 
162 	return pwm;
163 }
164 
pwm_probe(struct platform_device * pdev)165 static int pwm_probe(struct platform_device *pdev)
166 {
167 	const struct platform_device_id *id = platform_get_device_id(pdev);
168 	struct pxa_pwm_chip *pc;
169 	int ret = 0;
170 
171 	if (IS_ENABLED(CONFIG_OF) && id == NULL)
172 		id = pxa_pwm_get_id_dt(&pdev->dev);
173 
174 	if (id == NULL)
175 		return -EINVAL;
176 
177 	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
178 	if (pc == NULL)
179 		return -ENOMEM;
180 
181 	pc->clk = devm_clk_get(&pdev->dev, NULL);
182 	if (IS_ERR(pc->clk))
183 		return PTR_ERR(pc->clk);
184 
185 	pc->chip.dev = &pdev->dev;
186 	pc->chip.ops = &pxa_pwm_ops;
187 	pc->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
188 
189 	if (IS_ENABLED(CONFIG_OF)) {
190 		pc->chip.of_xlate = pxa_pwm_of_xlate;
191 		pc->chip.of_pwm_n_cells = 1;
192 	}
193 
194 	pc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
195 	if (IS_ERR(pc->mmio_base))
196 		return PTR_ERR(pc->mmio_base);
197 
198 	ret = devm_pwmchip_add(&pdev->dev, &pc->chip);
199 	if (ret < 0) {
200 		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
201 		return ret;
202 	}
203 
204 	return 0;
205 }
206 
207 static struct platform_driver pwm_driver = {
208 	.driver		= {
209 		.name	= "pxa25x-pwm",
210 		.of_match_table = pwm_of_match,
211 	},
212 	.probe		= pwm_probe,
213 	.id_table	= pwm_id_table,
214 };
215 
216 module_platform_driver(pwm_driver);
217 
218 MODULE_LICENSE("GPL v2");
219