Blackfin: pwm: implement linux/pwm.h API

For now, this only supports gptimers. Support for dedicated PWM devices
as found on newer parts to come.

Signed-off-by: Michael Hennerich <[e-mail]>
Signed-off-by: Mike Frysinger <[e-mail]>

arch/blackfin/Kconfig

···
 	  To compile this driver as a module, choose M here: the module
 	  will be called gptimers.
 
+config HAVE_PWM
+	tristate "Enable PWM API support"
+	depends on BFIN_GPTIMERS
+	help
+	  Enable support for the Pulse Width Modulation framework (as
+	  found in linux/pwm.h).
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm.
+
 choice
 	prompt "Uncached DMA region"
 	default DMA_UNCACHED_1M

arch/blackfin/kernel/Makefile

···
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER)  += ftrace.o
 CFLAGS_REMOVE_ftrace.o = -pg
 
+obj-$(CONFIG_HAVE_PWM)               += pwm.o
 obj-$(CONFIG_IPIPE)                  += ipipe.o
 obj-$(CONFIG_BFIN_GPTIMERS)          += gptimers.o
 obj-$(CONFIG_CPLB_INFO)              += cplbinfo.o

arch/blackfin/kernel/pwm.c

···
+/*
+ * Blackfin Pulse Width Modulation (PWM) core
+ *
+ * Copyright (c) 2011 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#include <asm/gptimers.h>
+#include <asm/portmux.h>
+
+struct pwm_device {
+	unsigned id;
+	unsigned short pin;
+};
+
+static const unsigned short pwm_to_gptimer_per[] = {
+	P_TMR0, P_TMR1, P_TMR2, P_TMR3, P_TMR4, P_TMR5,
+	P_TMR6, P_TMR7, P_TMR8, P_TMR9, P_TMR10, P_TMR11,
+};
+
+struct pwm_device *pwm_request(int pwm_id, const char *label)
+{
+	struct pwm_device *pwm;
+	int ret;
+
+	/* XXX: pwm_id really should be unsigned */
+	if (pwm_id < 0)
+		return NULL;
+
+	pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
+	if (!pwm)
+		return pwm;
+
+	pwm->id = pwm_id;
+	if (pwm->id >= ARRAY_SIZE(pwm_to_gptimer_per))
+		goto err;
+
+	pwm->pin = pwm_to_gptimer_per[pwm->id];
+	ret = peripheral_request(pwm->pin, label);
+	if (ret)
+		goto err;
+
+	return pwm;
+ err:
+	kfree(pwm);
+	return NULL;
+}
+EXPORT_SYMBOL(pwm_request);
+
+void pwm_free(struct pwm_device *pwm)
+{
+	peripheral_free(pwm->pin);
+	kfree(pwm);
+}
+EXPORT_SYMBOL(pwm_free);
+
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+	unsigned long period, duty;
+	unsigned long long val;
+
+	if (duty_ns < 0 || duty_ns > period_ns)
+		return -EINVAL;
+
+	val = (unsigned long long)get_sclk() * period_ns;
+	do_div(val, NSEC_PER_SEC);
+	period = val;
+
+	val = (unsigned long long)period * duty_ns;
+	do_div(val, period_ns);
+	duty = period - val;
+
+	if (duty >= period)
+		duty = period - 1;
+
+	set_gptimer_config(pwm->id, TIMER_MODE_PWM | TIMER_PERIOD_CNT);
+	set_gptimer_pwidth(pwm->id, duty);
+	set_gptimer_period(pwm->id, period);
+
+	return 0;
+}
+EXPORT_SYMBOL(pwm_config);
+
+int pwm_enable(struct pwm_device *pwm)
+{
+	enable_gptimer(pwm->id);
+	return 0;
+}
+EXPORT_SYMBOL(pwm_enable);
+
+void pwm_disable(struct pwm_device *pwm)
+{
+	disable_gptimer(pwm->id);
+}
+EXPORT_SYMBOL(pwm_disable);