1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * drivers/pwm/pwm-vt8500.c
4 *
5 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
6 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
7 */
8
9 #include <linux/mod_devicetable.h>
10 #include <linux/module.h>
11 #include <linux/kernel.h>
12 #include <linux/platform_device.h>
13 #include <linux/slab.h>
14 #include <linux/err.h>
15 #include <linux/io.h>
16 #include <linux/pwm.h>
17 #include <linux/delay.h>
18 #include <linux/clk.h>
19
20 #include <asm/div64.h>
21
22 /*
23 * SoC architecture allocates register space for 4 PWMs but only
24 * 2 are currently implemented.
25 */
26 #define VT8500_NR_PWMS 2
27
28 #define REG_CTRL(pwm) (((pwm) << 4) + 0x00)
29 #define REG_SCALAR(pwm) (((pwm) << 4) + 0x04)
30 #define REG_PERIOD(pwm) (((pwm) << 4) + 0x08)
31 #define REG_DUTY(pwm) (((pwm) << 4) + 0x0C)
32 #define REG_STATUS 0x40
33
34 #define CTRL_ENABLE BIT(0)
35 #define CTRL_INVERT BIT(1)
36 #define CTRL_AUTOLOAD BIT(2)
37 #define CTRL_STOP_IMM BIT(3)
38 #define CTRL_LOAD_PRESCALE BIT(4)
39 #define CTRL_LOAD_PERIOD BIT(5)
40
41 #define STATUS_CTRL_UPDATE BIT(0)
42 #define STATUS_SCALAR_UPDATE BIT(1)
43 #define STATUS_PERIOD_UPDATE BIT(2)
44 #define STATUS_DUTY_UPDATE BIT(3)
45 #define STATUS_ALL_UPDATE 0x0F
46
47 struct vt8500_chip {
48 void __iomem *base;
49 struct clk *clk;
50 };
51
to_vt8500_chip(struct pwm_chip * chip)52 static inline struct vt8500_chip *to_vt8500_chip(struct pwm_chip *chip)
53 {
54 return pwmchip_get_drvdata(chip);
55 }
56
57 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
vt8500_pwm_busy_wait(struct pwm_chip * chip,int nr,u8 bitmask)58 static inline void vt8500_pwm_busy_wait(struct pwm_chip *chip, int nr, u8 bitmask)
59 {
60 struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
61 int loops = msecs_to_loops(10);
62 u32 mask = bitmask << (nr << 8);
63
64 while ((readl(vt8500->base + REG_STATUS) & mask) && --loops)
65 cpu_relax();
66
67 if (unlikely(!loops))
68 dev_warn(pwmchip_parent(chip), "Waiting for status bits 0x%x to clear timed out\n",
69 mask);
70 }
71
vt8500_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,u64 duty_ns,u64 period_ns)72 static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
73 u64 duty_ns, u64 period_ns)
74 {
75 struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
76 unsigned long long c;
77 unsigned long period_cycles, prescale, pv, dc;
78 int err;
79 u32 val;
80
81 err = clk_enable(vt8500->clk);
82 if (err < 0) {
83 dev_err(pwmchip_parent(chip), "failed to enable clock\n");
84 return err;
85 }
86
87 c = clk_get_rate(vt8500->clk);
88 c = c * period_ns;
89 do_div(c, 1000000000);
90 period_cycles = c;
91
92 if (period_cycles < 1)
93 period_cycles = 1;
94 prescale = (period_cycles - 1) / 4096;
95 pv = period_cycles / (prescale + 1) - 1;
96 if (pv > 4095)
97 pv = 4095;
98
99 if (prescale > 1023) {
100 clk_disable(vt8500->clk);
101 return -EINVAL;
102 }
103
104 c = (unsigned long long)pv * duty_ns;
105
106 dc = div64_u64(c, period_ns);
107
108 writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
109 vt8500_pwm_busy_wait(chip, pwm->hwpwm, STATUS_SCALAR_UPDATE);
110
111 writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm));
112 vt8500_pwm_busy_wait(chip, pwm->hwpwm, STATUS_PERIOD_UPDATE);
113
114 writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm));
115 vt8500_pwm_busy_wait(chip, pwm->hwpwm, STATUS_DUTY_UPDATE);
116
117 val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
118 val |= CTRL_AUTOLOAD;
119 writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
120 vt8500_pwm_busy_wait(chip, pwm->hwpwm, STATUS_CTRL_UPDATE);
121
122 clk_disable(vt8500->clk);
123 return 0;
124 }
125
vt8500_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)126 static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
127 {
128 struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
129 int err;
130 u32 val;
131
132 err = clk_enable(vt8500->clk);
133 if (err < 0) {
134 dev_err(pwmchip_parent(chip), "failed to enable clock\n");
135 return err;
136 }
137
138 val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
139 val |= CTRL_ENABLE;
140 writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
141 vt8500_pwm_busy_wait(chip, pwm->hwpwm, STATUS_CTRL_UPDATE);
142
143 return 0;
144 }
145
vt8500_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)146 static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
147 {
148 struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
149 u32 val;
150
151 val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
152 val &= ~CTRL_ENABLE;
153 writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
154 vt8500_pwm_busy_wait(chip, pwm->hwpwm, STATUS_CTRL_UPDATE);
155
156 clk_disable(vt8500->clk);
157 }
158
vt8500_pwm_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)159 static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
160 struct pwm_device *pwm,
161 enum pwm_polarity polarity)
162 {
163 struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
164 u32 val;
165
166 val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
167
168 if (polarity == PWM_POLARITY_INVERSED)
169 val |= CTRL_INVERT;
170 else
171 val &= ~CTRL_INVERT;
172
173 writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
174 vt8500_pwm_busy_wait(chip, pwm->hwpwm, STATUS_CTRL_UPDATE);
175
176 return 0;
177 }
178
vt8500_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)179 static int vt8500_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
180 const struct pwm_state *state)
181 {
182 int err;
183 bool enabled = pwm->state.enabled;
184
185 if (state->polarity != pwm->state.polarity) {
186 /*
187 * Changing the polarity of a running PWM is only allowed when
188 * the PWM driver implements ->apply().
189 */
190 if (enabled) {
191 vt8500_pwm_disable(chip, pwm);
192
193 enabled = false;
194 }
195
196 err = vt8500_pwm_set_polarity(chip, pwm, state->polarity);
197 if (err)
198 return err;
199 }
200
201 if (!state->enabled) {
202 if (enabled)
203 vt8500_pwm_disable(chip, pwm);
204
205 return 0;
206 }
207
208 /*
209 * We cannot skip calling ->config even if state->period ==
210 * pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
211 * because we might have exited early in the last call to
212 * pwm_apply_might_sleep because of !state->enabled and so the two values in
213 * pwm->state might not be configured in hardware.
214 */
215 err = vt8500_pwm_config(chip, pwm, state->duty_cycle, state->period);
216 if (err)
217 return err;
218
219 if (!enabled)
220 err = vt8500_pwm_enable(chip, pwm);
221
222 return err;
223 }
224
225 static const struct pwm_ops vt8500_pwm_ops = {
226 .apply = vt8500_pwm_apply,
227 };
228
229 static const struct of_device_id vt8500_pwm_dt_ids[] = {
230 { .compatible = "via,vt8500-pwm", },
231 { /* Sentinel */ }
232 };
233 MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);
234
vt8500_pwm_probe(struct platform_device * pdev)235 static int vt8500_pwm_probe(struct platform_device *pdev)
236 {
237 struct pwm_chip *chip;
238 struct vt8500_chip *vt8500;
239 struct device_node *np = pdev->dev.of_node;
240 int ret;
241
242 if (!np)
243 return dev_err_probe(&pdev->dev, -EINVAL, "invalid devicetree node\n");
244
245 chip = devm_pwmchip_alloc(&pdev->dev, VT8500_NR_PWMS, sizeof(*vt8500));
246 if (IS_ERR(chip))
247 return PTR_ERR(chip);
248 vt8500 = to_vt8500_chip(chip);
249
250 chip->ops = &vt8500_pwm_ops;
251
252 vt8500->clk = devm_clk_get_prepared(&pdev->dev, NULL);
253 if (IS_ERR(vt8500->clk))
254 return dev_err_probe(&pdev->dev, PTR_ERR(vt8500->clk), "clock source not specified\n");
255
256 vt8500->base = devm_platform_ioremap_resource(pdev, 0);
257 if (IS_ERR(vt8500->base))
258 return PTR_ERR(vt8500->base);
259
260 ret = devm_pwmchip_add(&pdev->dev, chip);
261 if (ret < 0)
262 return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n");
263
264 return 0;
265 }
266
267 static struct platform_driver vt8500_pwm_driver = {
268 .probe = vt8500_pwm_probe,
269 .driver = {
270 .name = "vt8500-pwm",
271 .of_match_table = vt8500_pwm_dt_ids,
272 },
273 };
274 module_platform_driver(vt8500_pwm_driver);
275
276 MODULE_DESCRIPTION("VT8500 PWM Driver");
277 MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
278 MODULE_LICENSE("GPL v2");
279