2 * Intel Low Power Subsystem PWM controller driver
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>
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.
16 #include <linux/kernel.h>
17 #include <linux/module.h>
21 #define PWM 0x00000000
22 #define PWM_ENABLE BIT(31)
23 #define PWM_SW_UPDATE BIT(30)
24 #define PWM_BASE_UNIT_SHIFT 8
25 #define PWM_BASE_UNIT_MASK 0x00ffff00
26 #define PWM_ON_TIME_DIV_MASK 0x000000ff
27 #define PWM_DIVISION_CORRECTION 0x2
28 #define PWM_LIMIT (0x8000 + PWM_DIVISION_CORRECTION)
29 #define NSECS_PER_SEC 1000000000UL
31 struct pwm_lpss_chip
{
34 unsigned long clk_rate
;
38 const struct pwm_lpss_boardinfo pwm_lpss_byt_info
= {
41 EXPORT_SYMBOL_GPL(pwm_lpss_byt_info
);
44 const struct pwm_lpss_boardinfo pwm_lpss_bsw_info
= {
47 EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info
);
49 static inline struct pwm_lpss_chip
*to_lpwm(struct pwm_chip
*chip
)
51 return container_of(chip
, struct pwm_lpss_chip
, chip
);
54 static int pwm_lpss_config(struct pwm_chip
*chip
, struct pwm_device
*pwm
,
55 int duty_ns
, int period_ns
)
57 struct pwm_lpss_chip
*lpwm
= to_lpwm(chip
);
60 unsigned long long base_unit
, freq
= NSECS_PER_SEC
;
63 do_div(freq
, period_ns
);
65 /* The equation is: base_unit = ((freq / c) * 65536) + correction */
66 base_unit
= freq
* 65536;
73 base_unit
+= PWM_DIVISION_CORRECTION
;
74 if (base_unit
> PWM_LIMIT
)
79 on_time_div
= 255 - (255 * duty_ns
/ period_ns
);
81 ctrl
= readl(lpwm
->regs
+ PWM
);
82 ctrl
&= ~(PWM_BASE_UNIT_MASK
| PWM_ON_TIME_DIV_MASK
);
83 ctrl
|= (u16
) base_unit
<< PWM_BASE_UNIT_SHIFT
;
85 /* request PWM to update on next cycle */
86 ctrl
|= PWM_SW_UPDATE
;
87 writel(ctrl
, lpwm
->regs
+ PWM
);
92 static int pwm_lpss_enable(struct pwm_chip
*chip
, struct pwm_device
*pwm
)
94 struct pwm_lpss_chip
*lpwm
= to_lpwm(chip
);
97 ctrl
= readl(lpwm
->regs
+ PWM
);
98 writel(ctrl
| PWM_ENABLE
, lpwm
->regs
+ PWM
);
103 static void pwm_lpss_disable(struct pwm_chip
*chip
, struct pwm_device
*pwm
)
105 struct pwm_lpss_chip
*lpwm
= to_lpwm(chip
);
108 ctrl
= readl(lpwm
->regs
+ PWM
);
109 writel(ctrl
& ~PWM_ENABLE
, lpwm
->regs
+ PWM
);
112 static const struct pwm_ops pwm_lpss_ops
= {
113 .config
= pwm_lpss_config
,
114 .enable
= pwm_lpss_enable
,
115 .disable
= pwm_lpss_disable
,
116 .owner
= THIS_MODULE
,
119 struct pwm_lpss_chip
*pwm_lpss_probe(struct device
*dev
, struct resource
*r
,
120 const struct pwm_lpss_boardinfo
*info
)
122 struct pwm_lpss_chip
*lpwm
;
125 lpwm
= devm_kzalloc(dev
, sizeof(*lpwm
), GFP_KERNEL
);
127 return ERR_PTR(-ENOMEM
);
129 lpwm
->regs
= devm_ioremap_resource(dev
, r
);
130 if (IS_ERR(lpwm
->regs
))
131 return ERR_CAST(lpwm
->regs
);
133 lpwm
->clk_rate
= info
->clk_rate
;
134 lpwm
->chip
.dev
= dev
;
135 lpwm
->chip
.ops
= &pwm_lpss_ops
;
136 lpwm
->chip
.base
= -1;
139 ret
= pwmchip_add(&lpwm
->chip
);
141 dev_err(dev
, "failed to add PWM chip: %d\n", ret
);
147 EXPORT_SYMBOL_GPL(pwm_lpss_probe
);
149 int pwm_lpss_remove(struct pwm_lpss_chip
*lpwm
)
153 ctrl
= readl(lpwm
->regs
+ PWM
);
154 writel(ctrl
& ~PWM_ENABLE
, lpwm
->regs
+ PWM
);
156 return pwmchip_remove(&lpwm
->chip
);
158 EXPORT_SYMBOL_GPL(pwm_lpss_remove
);
160 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
161 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
162 MODULE_LICENSE("GPL v2");