xref: /openbmc/linux/drivers/pwm/pwm-lpss.c (revision 8a26af30) 
1 /*
2  * Intel Low Power Subsystem PWM controller driver
3  *
4  * Copyright (C) 2014, Intel Corporation
5  * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
6  * Author: Chew Kean Ho <kean.ho.chew@intel.com>
7  * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
8  * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
9  * Author: Alan Cox <alan@linux.intel.com>
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License version 2 as
13  * published by the Free Software Foundation.
14  */
15 
16 #include <linux/acpi.h>
17 #include <linux/clk.h>
18 #include <linux/device.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/pwm.h>
22 #include <linux/platform_device.h>
23 #include <linux/pci.h>
24 
25 static int pci_drv, plat_drv;	/* So we know which drivers registered */
26 
27 #define PWM				0x00000000
28 #define PWM_ENABLE			BIT(31)
29 #define PWM_SW_UPDATE			BIT(30)
30 #define PWM_BASE_UNIT_SHIFT		8
31 #define PWM_BASE_UNIT_MASK		0x00ffff00
32 #define PWM_ON_TIME_DIV_MASK		0x000000ff
33 #define PWM_DIVISION_CORRECTION		0x2
34 #define PWM_LIMIT			(0x8000 + PWM_DIVISION_CORRECTION)
35 #define NSECS_PER_SEC			1000000000UL
36 
37 struct pwm_lpss_chip {
38 	struct pwm_chip chip;
39 	void __iomem *regs;
40 	struct clk *clk;
41 	unsigned long clk_rate;
42 };
43 
44 struct pwm_lpss_boardinfo {
45 	unsigned long clk_rate;
46 };
47 
48 /* BayTrail */
49 static const struct pwm_lpss_boardinfo byt_info = {
50 	25000000
51 };
52 
53 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
54 {
55 	return container_of(chip, struct pwm_lpss_chip, chip);
56 }
57 
58 static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
59 			   int duty_ns, int period_ns)
60 {
61 	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
62 	u8 on_time_div;
63 	unsigned long c;
64 	unsigned long long base_unit, freq = NSECS_PER_SEC;
65 	u32 ctrl;
66 
67 	do_div(freq, period_ns);
68 
69 	/* The equation is: base_unit = ((freq / c) * 65536) + correction */
70 	base_unit = freq * 65536;
71 
72 	c = lpwm->clk_rate;
73 	if (!c)
74 		return -EINVAL;
75 
76 	do_div(base_unit, c);
77 	base_unit += PWM_DIVISION_CORRECTION;
78 	if (base_unit > PWM_LIMIT)
79 		return -EINVAL;
80 
81 	if (duty_ns <= 0)
82 		duty_ns = 1;
83 	on_time_div = 255 - (255 * duty_ns / period_ns);
84 
85 	ctrl = readl(lpwm->regs + PWM);
86 	ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
87 	ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
88 	ctrl |= on_time_div;
89 	/* request PWM to update on next cycle */
90 	ctrl |= PWM_SW_UPDATE;
91 	writel(ctrl, lpwm->regs + PWM);
92 
93 	return 0;
94 }
95 
96 static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
97 {
98 	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
99 	u32 ctrl;
100 	int ret;
101 
102 	ret = clk_prepare_enable(lpwm->clk);
103 	if (ret)
104 		return ret;
105 
106 	ctrl = readl(lpwm->regs + PWM);
107 	writel(ctrl | PWM_ENABLE, lpwm->regs + PWM);
108 
109 	return 0;
110 }
111 
112 static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
113 {
114 	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
115 	u32 ctrl;
116 
117 	ctrl = readl(lpwm->regs + PWM);
118 	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
119 
120 	clk_disable_unprepare(lpwm->clk);
121 }
122 
123 static const struct pwm_ops pwm_lpss_ops = {
124 	.config = pwm_lpss_config,
125 	.enable = pwm_lpss_enable,
126 	.disable = pwm_lpss_disable,
127 	.owner = THIS_MODULE,
128 };
129 
130 static struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev,
131 					    struct resource *r,
132 					    const struct pwm_lpss_boardinfo *info)
133 {
134 	struct pwm_lpss_chip *lpwm;
135 	int ret;
136 
137 	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
138 	if (!lpwm)
139 		return ERR_PTR(-ENOMEM);
140 
141 	lpwm->regs = devm_ioremap_resource(dev, r);
142 	if (IS_ERR(lpwm->regs))
143 		return ERR_CAST(lpwm->regs);
144 
145 	if (info) {
146 		lpwm->clk_rate = info->clk_rate;
147 	} else {
148 		lpwm->clk = devm_clk_get(dev, NULL);
149 		if (IS_ERR(lpwm->clk)) {
150 			dev_err(dev, "failed to get PWM clock\n");
151 			return ERR_CAST(lpwm->clk);
152 		}
153 		lpwm->clk_rate = clk_get_rate(lpwm->clk);
154 	}
155 
156 	lpwm->chip.dev = dev;
157 	lpwm->chip.ops = &pwm_lpss_ops;
158 	lpwm->chip.base = -1;
159 	lpwm->chip.npwm = 1;
160 
161 	ret = pwmchip_add(&lpwm->chip);
162 	if (ret) {
163 		dev_err(dev, "failed to add PWM chip: %d\n", ret);
164 		return ERR_PTR(ret);
165 	}
166 
167 	return lpwm;
168 }
169 
170 static int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
171 {
172 	u32 ctrl;
173 
174 	ctrl = readl(lpwm->regs + PWM);
175 	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
176 
177 	return pwmchip_remove(&lpwm->chip);
178 }
179 
180 static int pwm_lpss_probe_pci(struct pci_dev *pdev,
181 			      const struct pci_device_id *id)
182 {
183 	const struct pwm_lpss_boardinfo *info;
184 	struct pwm_lpss_chip *lpwm;
185 	int err;
186 
187 	err = pci_enable_device(pdev);
188 	if (err < 0)
189 		return err;
190 
191 	info = (struct pwm_lpss_boardinfo *)id->driver_data;
192 	lpwm = pwm_lpss_probe(&pdev->dev, &pdev->resource[0], info);
193 	if (IS_ERR(lpwm))
194 		return PTR_ERR(lpwm);
195 
196 	pci_set_drvdata(pdev, lpwm);
197 	return 0;
198 }
199 
200 static void pwm_lpss_remove_pci(struct pci_dev *pdev)
201 {
202 	struct pwm_lpss_chip *lpwm = pci_get_drvdata(pdev);
203 
204 	pwm_lpss_remove(lpwm);
205 	pci_disable_device(pdev);
206 }
207 
208 static struct pci_device_id pwm_lpss_pci_ids[] = {
209 	{ PCI_VDEVICE(INTEL, 0x0f08), (unsigned long)&byt_info},
210 	{ PCI_VDEVICE(INTEL, 0x0f09), (unsigned long)&byt_info},
211 	{ },
212 };
213 MODULE_DEVICE_TABLE(pci, pwm_lpss_pci_ids);
214 
215 static struct pci_driver pwm_lpss_driver_pci = {
216 	.name = "pwm-lpss",
217 	.id_table = pwm_lpss_pci_ids,
218 	.probe = pwm_lpss_probe_pci,
219 	.remove = pwm_lpss_remove_pci,
220 };
221 
222 static int pwm_lpss_probe_platform(struct platform_device *pdev)
223 {
224 	struct pwm_lpss_chip *lpwm;
225 	struct resource *r;
226 
227 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
228 
229 	lpwm = pwm_lpss_probe(&pdev->dev, r, NULL);
230 	if (IS_ERR(lpwm))
231 		return PTR_ERR(lpwm);
232 
233 	platform_set_drvdata(pdev, lpwm);
234 	return 0;
235 }
236 
237 static int pwm_lpss_remove_platform(struct platform_device *pdev)
238 {
239 	struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
240 
241 	return pwm_lpss_remove(lpwm);
242 }
243 
244 static const struct acpi_device_id pwm_lpss_acpi_match[] = {
245 	{ "80860F09", 0 },
246 	{ },
247 };
248 MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);
249 
250 static struct platform_driver pwm_lpss_driver_platform = {
251 	.driver = {
252 		.name = "pwm-lpss",
253 		.acpi_match_table = pwm_lpss_acpi_match,
254 	},
255 	.probe = pwm_lpss_probe_platform,
256 	.remove = pwm_lpss_remove_platform,
257 };
258 
259 static int __init pwm_init(void)
260 {
261 	pci_drv = pci_register_driver(&pwm_lpss_driver_pci);
262 	plat_drv = platform_driver_register(&pwm_lpss_driver_platform);
263 	if (pci_drv && plat_drv)
264 		return pci_drv;
265 
266 	return 0;
267 }
268 module_init(pwm_init);
269 
270 static void __exit pwm_exit(void)
271 {
272 	if (!pci_drv)
273 		pci_unregister_driver(&pwm_lpss_driver_pci);
274 	if (!plat_drv)
275 		platform_driver_unregister(&pwm_lpss_driver_platform);
276 }
277 module_exit(pwm_exit);
278 
279 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
280 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
281 MODULE_LICENSE("GPL v2");
282 MODULE_ALIAS("platform:pwm-lpss");
283