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authorHolger Schurig <h.schurig@mn-solutions.de>2009-04-14 06:50:20 -0400
committerSascha Hauer <s.hauer@pengutronix.de>2009-05-07 10:16:38 -0400
commitc010dba89bc0f5585550877b1693d11d24063b6b (patch)
tree65a1c28690a5371c54259fb367b02392c32b36c6
parent6b91edde09fadde2657b11b454b88ae89c5b4cae (diff)
imx: re-work of PWM, add i.MX21 support
* Kconfig enables now HAVE_PWM (this enables in turn the selection of CONFIG_BACKLIGHT_PWM) * changes CONFIG_ARCH_MXyy to CONFIG_MACH_MXyy * fix some register names to match those of the reference manual * write a stub code so that the PWM can be used to program the LCD backlight * convert from #ifdef CONFIG_ARCH_MXxx to cpu_is_mxXX() * remove unneeded defines and fix 80-column "violations" of checkpatch.pl Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat
-rw-r--r--arch/arm/plat-mxc/Kconfig1
-rw-r--r--arch/arm/plat-mxc/pwm.c144
2 files changed, 63 insertions, 82 deletions
diff --git a/arch/arm/plat-mxc/Kconfig b/arch/arm/plat-mxc/Kconfig
index 61acd4ca9349..beeb01aa029c 100644
--- a/arch/arm/plat-mxc/Kconfig
+++ b/arch/arm/plat-mxc/Kconfig
@@ -48,6 +48,7 @@ config MXC_IRQ_PRIOR
48config MXC_PWM 48config MXC_PWM
49 tristate "Enable PWM driver" 49 tristate "Enable PWM driver"
50 depends on ARCH_MXC 50 depends on ARCH_MXC
51 select HAVE_PWM
51 help 52 help
52 Enable support for the i.MX PWM controller(s). 53 Enable support for the i.MX PWM controller(s).
53 54
diff --git a/arch/arm/plat-mxc/pwm.c b/arch/arm/plat-mxc/pwm.c
index 9bffbc507cc2..ae34198a79dd 100644
--- a/arch/arm/plat-mxc/pwm.c
+++ b/arch/arm/plat-mxc/pwm.c
@@ -15,65 +15,26 @@
15#include <linux/clk.h> 15#include <linux/clk.h>
16#include <linux/io.h> 16#include <linux/io.h>
17#include <linux/pwm.h> 17#include <linux/pwm.h>
18#include <mach/hardware.h>
19
20
21/* i.MX1 and i.MX21 share the same PWM function block: */
22
23#define MX1_PWMC 0x00 /* PWM Control Register */
24#define MX1_PWMS 0x04 /* PWM Sample Register */
25#define MX1_PWMP 0x08 /* PWM Period Register */
26
27
28/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
29
30#define MX3_PWMCR 0x00 /* PWM Control Register */
31#define MX3_PWMSAR 0x0C /* PWM Sample Register */
32#define MX3_PWMPR 0x10 /* PWM Period Register */
33#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
34#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
35#define MX3_PWMCR_EN (1 << 0)
36
18 37
19#if defined CONFIG_ARCH_MX1 || defined CONFIG_ARCH_MX21
20#define PWM_VER_1
21
22#define PWMCR 0x00 /* PWM Control Register */
23#define PWMSR 0x04 /* PWM Sample Register */
24#define PWMPR 0x08 /* PWM Period Register */
25#define PWMCNR 0x0C /* PWM Counter Register */
26
27#define PWMCR_HCTR (1 << 18) /* Halfword FIFO Data Swapping */
28#define PWMCR_BCTR (1 << 17) /* Byte FIFO Data Swapping */
29#define PWMCR_SWR (1 << 16) /* Software Reset */
30#define PWMCR_CLKSRC_PERCLK (0 << 15) /* PERCLK Clock Source */
31#define PWMCR_CLKSRC_CLK32 (1 << 15) /* 32KHz Clock Source */
32#define PWMCR_PRESCALER(x) (((x - 1) & 0x7F) << 8) /* PRESCALER */
33#define PWMCR_IRQ (1 << 7) /* Interrupt Request */
34#define PWMCR_IRQEN (1 << 6) /* Interrupt Request Enable */
35#define PWMCR_FIFOAV (1 << 5) /* FIFO Available */
36#define PWMCR_EN (1 << 4) /* Enables/Disables the PWM */
37#define PWMCR_REPEAT(x) (((x) & 0x03) << 2) /* Sample Repeats */
38#define PWMCR_DIV(x) (((x) & 0x03) << 0) /* Clock divider 2/4/8/16 */
39
40#define MAX_DIV (128 * 16)
41#endif
42
43#if defined CONFIG_MACH_MX27 || defined CONFIG_ARCH_MX31
44#define PWM_VER_2
45
46#define PWMCR 0x00 /* PWM Control Register */
47#define PWMSR 0x04 /* PWM Status Register */
48#define PWMIR 0x08 /* PWM Interrupt Register */
49#define PWMSAR 0x0C /* PWM Sample Register */
50#define PWMPR 0x10 /* PWM Period Register */
51#define PWMCNR 0x14 /* PWM Counter Register */
52
53#define PWMCR_EN (1 << 0) /* Enables/Disables the PWM */
54#define PWMCR_REPEAT(x) (((x) & 0x03) << 1) /* Sample Repeats */
55#define PWMCR_SWR (1 << 3) /* Software Reset */
56#define PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)/* PRESCALER */
57#define PWMCR_CLKSRC(x) (((x) & 0x3) << 16)
58#define PWMCR_CLKSRC_OFF (0 << 16)
59#define PWMCR_CLKSRC_IPG (1 << 16)
60#define PWMCR_CLKSRC_IPG_HIGH (2 << 16)
61#define PWMCR_CLKSRC_CLK32 (3 << 16)
62#define PWMCR_POUTC
63#define PWMCR_HCTR (1 << 20) /* Halfword FIFO Data Swapping */
64#define PWMCR_BCTR (1 << 21) /* Byte FIFO Data Swapping */
65#define PWMCR_DBGEN (1 << 22) /* Debug Mode */
66#define PWMCR_WAITEN (1 << 23) /* Wait Mode */
67#define PWMCR_DOZEN (1 << 24) /* Doze Mode */
68#define PWMCR_STOPEN (1 << 25) /* Stop Mode */
69#define PWMCR_FWM(x) (((x) & 0x3) << 26) /* FIFO Water Mark */
70
71#define MAX_DIV 4096
72#endif
73
74#define PWMS_SAMPLE(x) ((x) & 0xFFFF) /* Contains a two-sample word */
75#define PWMP_PERIOD(x) ((x) & 0xFFFF) /* Represents the PWM's period */
76#define PWMC_COUNTER(x) ((x) & 0xFFFF) /* Represents the current count value */
77 38
78struct pwm_device { 39struct pwm_device {
79 struct list_head node; 40 struct list_head node;
@@ -91,32 +52,52 @@ struct pwm_device {
91 52
92int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) 53int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
93{ 54{
94 unsigned long long c;
95 unsigned long period_cycles, duty_cycles, prescale;
96
97 if (pwm == NULL || period_ns == 0 || duty_ns > period_ns) 55 if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
98 return -EINVAL; 56 return -EINVAL;
99 57
100 c = clk_get_rate(pwm->clk); 58 if (cpu_is_mx27() || cpu_is_mx3()) {
101 c = c * period_ns; 59 unsigned long long c;
102 do_div(c, 1000000000); 60 unsigned long period_cycles, duty_cycles, prescale;
103 period_cycles = c; 61 c = clk_get_rate(pwm->clk);
104 62 c = c * period_ns;
105 prescale = period_cycles / 0x10000 + 1; 63 do_div(c, 1000000000);
106 64 period_cycles = c;
107 period_cycles /= prescale; 65
108 c = (unsigned long long)period_cycles * duty_ns; 66 prescale = period_cycles / 0x10000 + 1;
109 do_div(c, period_ns); 67
110 duty_cycles = c; 68 period_cycles /= prescale;
111 69 c = (unsigned long long)period_cycles * duty_ns;
112#ifdef PWM_VER_2 70 do_div(c, period_ns);
113 writel(duty_cycles, pwm->mmio_base + PWMSAR); 71 duty_cycles = c;
114 writel(period_cycles, pwm->mmio_base + PWMPR); 72
115 writel(PWMCR_PRESCALER(prescale - 1) | PWMCR_CLKSRC_IPG_HIGH | PWMCR_EN, 73 writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
116 pwm->mmio_base + PWMCR); 74 writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
117#elif defined PWM_VER_1 75 writel(MX3_PWMCR_PRESCALER(prescale - 1) |
118#error PWM not yet working on MX1 / MX21 76 MX3_PWMCR_CLKSRC_IPG_HIGH | MX3_PWMCR_EN,
119#endif 77 pwm->mmio_base + MX3_PWMCR);
78 } else if (cpu_is_mx1() || cpu_is_mx21()) {
79 /* The PWM subsystem allows for exact frequencies. However,
80 * I cannot connect a scope on my device to the PWM line and
81 * thus cannot provide the program the PWM controller
82 * exactly. Instead, I'm relying on the fact that the
83 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
84 * function group already. So I'll just modify the PWM sample
85 * register to follow the ratio of duty_ns vs. period_ns
86 * accordingly.
87 *
88 * This is good enought for programming the brightness of
89 * the LCD backlight.
90 *
91 * The real implementation would divide PERCLK[0] first by
92 * both the prescaler (/1 .. /128) and then by CLKSEL
93 * (/2 .. /16).
94 */
95 u32 max = readl(pwm->mmio_base + MX1_PWMP);
96 u32 p = max * duty_ns / period_ns;
97 writel(max - p, pwm->mmio_base + MX1_PWMS);
98 } else {
99 BUG();
100 }
120 101
121 return 0; 102 return 0;
122} 103}
@@ -297,4 +278,3 @@ module_exit(mxc_pwm_exit);
297 278
298MODULE_LICENSE("GPL v2"); 279MODULE_LICENSE("GPL v2");
299MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); 280MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
300
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