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 <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

3 files changed, 111 insertions, 0 deletions

diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index d619b17c4413..c7476295de80 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -953,6 +953,16 @@ config BFIN_GPTIMERS
           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
diff --git a/arch/blackfin/kernel/Makefile b/arch/blackfin/kernel/Makefile
index d550b24d9e9b..b7bdc42fe1a3 100644
--- a/arch/blackfin/kernel/Makefile
+++ b/arch/blackfin/kernel/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_FUNCTION_TRACER)        += ftrace-entry.o
 obj-$(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
diff --git a/arch/blackfin/kernel/pwm.c b/arch/blackfin/kernel/pwm.c
new file mode 100644
index 000000000000..33f5942733bd
--- /dev/null
+++ b/arch/blackfin/kernel/pwm.c
@@ -0,0 +1,100 @@
+/*
+ * 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);