2 * simple driver for PWM (Pulse Width Modulator) controller
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
8 * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
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>
18 #include <linux/pwm.h>
19 #include <mach/hardware.h>
22 /* i.MX1 and i.MX21 share the same PWM function block: */
24 #define MX1_PWMC 0x00 /* PWM Control Register */
25 #define MX1_PWMS 0x04 /* PWM Sample Register */
26 #define MX1_PWMP 0x08 /* PWM Period Register */
29 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
31 #define MX3_PWMCR 0x00 /* PWM Control Register */
32 #define MX3_PWMSAR 0x0C /* PWM Sample Register */
33 #define MX3_PWMPR 0x10 /* PWM Period Register */
34 #define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
35 #define MX3_PWMCR_DOZEEN (1 << 24)
36 #define MX3_PWMCR_WAITEN (1 << 23)
37 #define MX3_PWMCR_DBGEN (1 << 22)
38 #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
39 #define MX3_PWMCR_CLKSRC_IPG (1 << 16)
40 #define MX3_PWMCR_EN (1 << 0)
46 void __iomem
*mmio_base
;
51 #define to_imx_chip(chip) container_of(chip, struct imx_chip, chip)
53 static int imx_pwm_config(struct pwm_chip
*chip
,
54 struct pwm_device
*pwm
, int duty_ns
, int period_ns
)
56 struct imx_chip
*imx
= to_imx_chip(chip
);
58 if (!(cpu_is_mx1() || cpu_is_mx21())) {
60 unsigned long period_cycles
, duty_cycles
, prescale
;
63 c
= clk_get_rate(imx
->clk
);
65 do_div(c
, 1000000000);
68 prescale
= period_cycles
/ 0x10000 + 1;
70 period_cycles
/= prescale
;
71 c
= (unsigned long long)period_cycles
* duty_ns
;
76 * according to imx pwm RM, the real period value should be
77 * PERIOD value in PWMPR plus 2.
79 if (period_cycles
> 2)
84 writel(duty_cycles
, imx
->mmio_base
+ MX3_PWMSAR
);
85 writel(period_cycles
, imx
->mmio_base
+ MX3_PWMPR
);
87 cr
= MX3_PWMCR_PRESCALER(prescale
) |
88 MX3_PWMCR_DOZEEN
| MX3_PWMCR_WAITEN
|
89 MX3_PWMCR_DBGEN
| MX3_PWMCR_EN
;
92 cr
|= MX3_PWMCR_CLKSRC_IPG
;
94 cr
|= MX3_PWMCR_CLKSRC_IPG_HIGH
;
96 writel(cr
, imx
->mmio_base
+ MX3_PWMCR
);
97 } else if (cpu_is_mx1() || cpu_is_mx21()) {
98 /* The PWM subsystem allows for exact frequencies. However,
99 * I cannot connect a scope on my device to the PWM line and
100 * thus cannot provide the program the PWM controller
101 * exactly. Instead, I'm relying on the fact that the
102 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
103 * function group already. So I'll just modify the PWM sample
104 * register to follow the ratio of duty_ns vs. period_ns
107 * This is good enough for programming the brightness of
110 * The real implementation would divide PERCLK[0] first by
111 * both the prescaler (/1 .. /128) and then by CLKSEL
114 u32 max
= readl(imx
->mmio_base
+ MX1_PWMP
);
115 u32 p
= max
* duty_ns
/ period_ns
;
116 writel(max
- p
, imx
->mmio_base
+ MX1_PWMS
);
124 static int imx_pwm_enable(struct pwm_chip
*chip
, struct pwm_device
*pwm
)
126 struct imx_chip
*imx
= to_imx_chip(chip
);
129 if (!imx
->clk_enabled
) {
130 rc
= clk_prepare_enable(imx
->clk
);
132 imx
->clk_enabled
= 1;
137 static void imx_pwm_disable(struct pwm_chip
*chip
, struct pwm_device
*pwm
)
139 struct imx_chip
*imx
= to_imx_chip(chip
);
141 writel(0, imx
->mmio_base
+ MX3_PWMCR
);
143 if (imx
->clk_enabled
) {
144 clk_disable_unprepare(imx
->clk
);
145 imx
->clk_enabled
= 0;
149 static struct pwm_ops imx_pwm_ops
= {
150 .enable
= imx_pwm_enable
,
151 .disable
= imx_pwm_disable
,
152 .config
= imx_pwm_config
,
153 .owner
= THIS_MODULE
,
156 static int __devinit
imx_pwm_probe(struct platform_device
*pdev
)
158 struct imx_chip
*imx
;
162 imx
= devm_kzalloc(&pdev
->dev
, sizeof(*imx
), GFP_KERNEL
);
164 dev_err(&pdev
->dev
, "failed to allocate memory\n");
168 imx
->clk
= devm_clk_get(&pdev
->dev
, "pwm");
170 if (IS_ERR(imx
->clk
))
171 return PTR_ERR(imx
->clk
);
173 imx
->chip
.ops
= &imx_pwm_ops
;
174 imx
->chip
.dev
= &pdev
->dev
;
178 imx
->clk_enabled
= 0;
180 r
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
182 dev_err(&pdev
->dev
, "no memory resource defined\n");
186 imx
->mmio_base
= devm_request_and_ioremap(&pdev
->dev
, r
);
187 if (imx
->mmio_base
== NULL
)
188 return -EADDRNOTAVAIL
;
190 ret
= pwmchip_add(&imx
->chip
);
194 platform_set_drvdata(pdev
, imx
);
198 static int __devexit
imx_pwm_remove(struct platform_device
*pdev
)
200 struct imx_chip
*imx
;
202 imx
= platform_get_drvdata(pdev
);
206 return pwmchip_remove(&imx
->chip
);
209 static struct platform_driver imx_pwm_driver
= {
213 .probe
= imx_pwm_probe
,
214 .remove
= __devexit_p(imx_pwm_remove
),
217 static int __init
imx_pwm_init(void)
219 return platform_driver_register(&imx_pwm_driver
);
221 arch_initcall(imx_pwm_init
);
223 static void __exit
imx_pwm_exit(void)
225 platform_driver_unregister(&imx_pwm_driver
);
227 module_exit(imx_pwm_exit
);
229 MODULE_LICENSE("GPL v2");
230 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");