[PATCH] drivers/pwm: add PXA pulse width modulator controller
Robert Jarzmik
robert.jarzmik at free.fr
Wed Feb 1 17:42:28 EST 2012
Add PXA embedded pulse width modulator support. The PWM can
generate signals from 49.6kHz to 1.625MHz.
The driver is for pxa2xx family. The pxa3xx was not handled yet.
Signed-off-by: Robert Jarzmik <robert.jarzmik at free.fr>
---
arch/arm/mach-pxa/Makefile | 1 +
arch/arm/mach-pxa/include/mach/clock.h | 1 +
arch/arm/mach-pxa/include/mach/regs-pwm.h | 20 ++++
arch/arm/mach-pxa/speed-pxa27x.c | 5 +
drivers/pwm/Kconfig | 6 +
drivers/pwm/Makefile | 1 +
drivers/pwm/pxa_pwm.c | 163 +++++++++++++++++++++++++++++
7 files changed, 197 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/mach-pxa/include/mach/regs-pwm.h
create mode 100644 drivers/pwm/pxa_pwm.c
diff --git a/arch/arm/mach-pxa/Makefile b/arch/arm/mach-pxa/Makefile
index c01a9e0..6a02a54 100644
--- a/arch/arm/mach-pxa/Makefile
+++ b/arch/arm/mach-pxa/Makefile
@@ -1,6 +1,7 @@
obj-y += clocksource.o
obj-y += common.o
obj-y += gpio.o
+obj-y += devices.o
obj-$(CONFIG_ARCH_PXA2XX) += mfp-pxa2xx.o
obj-$(CONFIG_ARCH_PXA27X) += speed-pxa27x.o
diff --git a/arch/arm/mach-pxa/include/mach/clock.h b/arch/arm/mach-pxa/include/mach/clock.h
index c53432f..f86152f 100644
--- a/arch/arm/mach-pxa/include/mach/clock.h
+++ b/arch/arm/mach-pxa/include/mach/clock.h
@@ -14,5 +14,6 @@
unsigned long pxa_get_uartclk(void);
unsigned long pxa_get_mmcclk(void);
unsigned long pxa_get_lcdclk(void);
+unsigned long pxa_get_pwmclk(void);
#endif /* !__MACH_CLOCK_H */
diff --git a/arch/arm/mach-pxa/include/mach/regs-pwm.h b/arch/arm/mach-pxa/include/mach/regs-pwm.h
new file mode 100644
index 0000000..9fdcbb6
--- /dev/null
+++ b/arch/arm/mach-pxa/include/mach/regs-pwm.h
@@ -0,0 +1,20 @@
+/*
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef __ASM_MACH_REGS_PWM_H
+#define __ASM_MACH_REGS_PWM_H
+
+#include <mach/hardware.h>
+
+/*
+ * Pulse modulator registers
+ */
+#define PWM0 0x40B00000
+#define PWM1 0x40C00000
+#define PWM0slave 0x40B00010
+#define PWM1slave 0x40C00010
+
+#endif
diff --git a/arch/arm/mach-pxa/speed-pxa27x.c b/arch/arm/mach-pxa/speed-pxa27x.c
index 534eb1d..1de034c 100644
--- a/arch/arm/mach-pxa/speed-pxa27x.c
+++ b/arch/arm/mach-pxa/speed-pxa27x.c
@@ -47,3 +47,8 @@ unsigned long pxa_get_lcdclk(void)
{
return pxa_get_lcdclk_10khz() * 10000;
}
+
+unsigned long pxa_get_pwmclk(void)
+{
+ return BASE_CLK;
+}
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 93c1052..50c956a 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -8,5 +8,11 @@ menuconfig PWM
If unsure, say N.
if PWM
+config PWM_PXA
+ bool "PXA PWM Support"
+ default y if ARCH_PXA2XX
+ help
+ This enables PWM support for Intel/Marvell PXA chips, such
+ as the PXA25x, PXA27x.
endif
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 3469c3d..c886bd5 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -1 +1,2 @@
obj-$(CONFIG_PWM) += core.o
+obj-$(CONFIG_PWM_PXA) += pxa_pwm.o
\ No newline at end of file
diff --git a/drivers/pwm/pxa_pwm.c b/drivers/pwm/pxa_pwm.c
new file mode 100644
index 0000000..bb114aa
--- /dev/null
+++ b/drivers/pwm/pxa_pwm.c
@@ -0,0 +1,163 @@
+/*
+ * simple driver for PWM (Pulse Width Modulator) controller
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 2008-02-13 initial version
+ * eric miao <eric.miao at marvell.com>
+ * 2012 Robert Jarzmik <robert.jarzmik at free.fr>
+ */
+
+#include <common.h>
+#include <init.h>
+#include <errno.h>
+#include <io.h>
+#include <pwm.h>
+
+#include <mach/hardware.h>
+#include <mach/clock.h>
+#include <mach/pxa-regs.h>
+#include <mach/regs-pwm.h>
+#include <asm-generic/div64.h>
+#include <linux/compiler.h>
+
+/* PWM registers and bits definitions */
+#define PWMCR (0x00)
+#define PWMDCR (0x04)
+#define PWMPCR (0x08)
+
+#define PWMCR_SD (1 << 6)
+#define PWMDCR_FD (1 << 10)
+
+#ifdef CONFIG_PWM
+
+static int pwm_get_pwm_idx(struct pwm_chip *chip)
+{
+ if (!strncmp(chip->devname, "pxa_pwm0", 8))
+ return 0;
+ else if (!strncmp(chip->devname, "pxa_pwm1", 8))
+ return 1;
+ else
+ return -EINVAL;
+}
+
+static void __iomem *pwm_bases[] = {
+ (void __iomem *)PWM0,
+ (void __iomem *)PWM1,
+ (void __iomem *)PWM0slave,
+ (void __iomem *)PWM1slave,
+};
+
+/*
+ * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
+ * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
+ * PWM_CLK_RATE = 13 MHz
+ */
+static int pxa_pwm_config(struct pwm_chip *chip, int duty_ns, int period_ns)
+{
+ int pwm_idx;
+ unsigned long long c;
+ unsigned long period_cycles, prescale, pv, dc;
+ void __iomem *iobase;
+
+ pwm_idx = pwm_get_pwm_idx(chip);
+ if (pwm_idx < 0 || period_ns == 0 || duty_ns > period_ns)
+ return -EINVAL;
+ iobase = pwm_bases[pwm_idx];
+
+ c = pxa_get_pwmclk();
+ c = c * period_ns;
+ do_div(c, 1000000000);
+ period_cycles = c;
+
+ if (period_cycles < 1)
+ period_cycles = 1;
+ prescale = (period_cycles - 1) / 1024;
+ pv = period_cycles / (prescale + 1) - 1;
+
+ if (prescale > 63)
+ return -EINVAL;
+
+ if (duty_ns == period_ns)
+ dc = PWMDCR_FD;
+ else
+ dc = (pv + 1) * duty_ns / period_ns;
+
+ /* NOTE: the clock to PWM has to be enabled first
+ * before writing to the registers
+ */
+ __raw_writel(prescale, iobase + PWMCR);
+ __raw_writel(dc, iobase + PWMDCR);
+ __raw_writel(pv, iobase + PWMPCR);
+
+ return 0;
+}
+
+static int pxa_pwm_enable(struct pwm_chip *chip)
+{
+ switch (pwm_get_pwm_idx(chip)) {
+ case 0:
+ CKEN |= CKEN_PWM0;
+ break;
+ case 1:
+ CKEN |= CKEN_PWM1;
+ break;
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static void pxa_pwm_disable(struct pwm_chip *chip)
+{
+ switch (pwm_get_pwm_idx(chip)) {
+ case 0:
+ CKEN &= ~CKEN_PWM0;
+ break;
+ case 1:
+ CKEN &= ~CKEN_PWM1;
+ break;
+ default:
+ break;
+ }
+}
+
+static struct pwm_ops pxa_pwm_ops = {
+ .config = pxa_pwm_config,
+ .enable = pxa_pwm_enable,
+ .disable = pxa_pwm_disable,
+};
+
+#define DECLARE_PXA_PWM(name) \
+ static struct pwm_chip name = { \
+ .devname = #name, \
+ .ops = &pxa_pwm_ops, \
+}
+
+DECLARE_PXA_PWM(pxa_pwm0);
+DECLARE_PXA_PWM(pxa_pwm1);
+DECLARE_PXA_PWM(pxa_pwm0slave);
+DECLARE_PXA_PWM(pxa_pwm1slave);
+
+static int pxa_pwm_init(void)
+{
+ CKEN &= ~CKEN_PWM0 & ~CKEN_PWM1;
+ pwmchip_add(&pxa_pwm0);
+ pwmchip_add(&pxa_pwm1);
+ if (cpu_is_pxa27x()) {
+ pwmchip_add(&pxa_pwm0slave);
+ pwmchip_add(&pxa_pwm1slave);
+ }
+ return 0;
+}
+
+#else
+static int pxa_pwm_init(void)
+{
+ return 0;
+}
+#endif
+
+coredevice_initcall(pxa_pwm_init);
--
1.7.5.4
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