zephyr: add PWM shim

Adds PWM shim to connect the platform/ec PWM API to the Zephyr PWM API.

BUG=b:174850923
BRANCH=none
TEST=make buildall
TEST=Run "pwmduty" command against Volteer LEDs

Signed-off-by: Keith Short <keithshort@chromium.org>
Change-Id: I49047734bc1a3fb3d4010f0040145171275c5657
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2623163
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>

10 files changed, 308 insertions, 1 deletions

diff --git a/common/pwm.c b/common/pwm.c
index 73b12fc20c..41989a94e0 100644
--- a/common/pwm.c
+++ b/common/pwm.c
@@ -11,6 +11,10 @@
 #include "pwm.h"
 #include "util.h"
 
+#ifdef CONFIG_ZEPHYR
+#include "pwm/pwm.h"
+#endif
+
 #ifdef CONFIG_PWM
 
 /*
@@ -162,10 +166,15 @@ DECLARE_CONSOLE_COMMAND(pwmduty, cc_pwm_duty,
 			"Get/set PWM duty cycles ");
 #endif /* CONFIG_PWM */
 
-/* Initialize all PWM pins as functional */
+#ifndef CONFIG_ZEPHYR
+/*
+ * Initialize all PWM pins as functional.  This is not required under
+ * Zephyr as pin configuration is automatically performed by chip driver
+ */
 static void pwm_pin_init(void)
 {
 	gpio_config_module(MODULE_PWM, 1);
 }
 /* HOOK_PRIO_INIT_PWM may be used for chip PWM unit init, so use PRIO + 1 */
 DECLARE_HOOK(HOOK_INIT, pwm_pin_init, HOOK_PRIO_INIT_PWM + 1);
+#endif /* CONFIG_ZEPHYR */
diff --git a/zephyr/CMakeLists.txt b/zephyr/CMakeLists.txt
index 7a62e4d7e4..a23a862f57 100644
--- a/zephyr/CMakeLists.txt
+++ b/zephyr/CMakeLists.txt
@@ -155,6 +155,7 @@ zephyr_sources_ifdef(CONFIG_PLATFORM_EC_THROTTLE_AP
                                                 "${PLATFORM_EC}/common/throttle_ap.c")
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_TABLET_MODE
                                                 "${PLATFORM_EC}/common/tablet_mode.c")
+zephyr_sources_ifdef(CONFIG_PLATFORM_EC_PWM     "${PLATFORM_EC}/common/pwm.c")
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_TIMER   "${PLATFORM_EC}/common/timer.c")
 
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_USB_CHARGER
diff --git a/zephyr/Kconfig b/zephyr/Kconfig
index 9a318358a0..e74aa487c7 100644
--- a/zephyr/Kconfig
+++ b/zephyr/Kconfig
@@ -453,6 +453,13 @@ config PLATFORM_EC_POWER_BUTTON
 
 	  This requires a GPIO named GPIO_POWER_BUTTON_L in gpio_map.h.
 
+config PLATFORM_EC_PWM
+	bool "PWM (Pulse Width Modulation) module"
+	help
+	  Enable the PWM (Pulse Width Modulation) module. This module is used to
+	  support variable brightness LEDs, backlight controls, and
+	  variable-speed fans.
+
 config PLATFORM_EC_CONSOLE_CMD_SHMEM
 	bool "Console command: shmem"
 	default y
diff --git a/zephyr/dts/bindings/pwm/named-pwms.yaml b/zephyr/dts/bindings/pwm/named-pwms.yaml
new file mode 100644
index 0000000000..f01fd5a30a
--- /dev/null
+++ b/zephyr/dts/bindings/pwm/named-pwms.yaml
@@ -0,0 +1,24 @@
+# Copyright 2021 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+description: PWM KEYS parent node
+
+compatible: "named-pwms"
+
+child-binding:
+  description: Named PWMs child node
+  properties:
+    pwms:
+      type: phandle-array
+      required: true
+    label:
+      required: true
+      type: string
+      description:
+        Human readable string describing the device (used as
+        device_get_binding() argument)
+    frequency:
+      required: true
+      type: int
+      description: PWM frequency, in Hz
diff --git a/zephyr/projects/volteer/boards/arm/volteer/volteer.dts b/zephyr/projects/volteer/boards/arm/volteer/volteer.dts
index e35b59240c..59cc5f2cbc 100644
--- a/zephyr/projects/volteer/boards/arm/volteer/volteer.dts
+++ b/zephyr/projects/volteer/boards/arm/volteer/volteer.dts
@@ -57,6 +57,31 @@
 		};
 	};
 
+	named-pwms {
+		compatible = "named-pwms";
+
+		led1_blue {
+			pwms = <&pwm2 0 PWM_POLARITY_INVERTED>;
+			label = "LED1_BLUE";
+			frequency = <4800>;
+		};
+		led2_green  {
+			pwms = <&pwm0 0 PWM_POLARITY_INVERTED>;
+			label = "LED2_GREEN";
+			frequency = <4800>;
+		};
+		led3_red {
+			pwms = <&pwm1 0 PWM_POLARITY_INVERTED>;
+			label = "LED3_RED";
+			frequency = <4800>;
+		};
+		led3_sidesel {
+			pwms = <&pwm7 0 PWM_POLARITY_INVERTED>;
+			label = "LED4_SIDESEL";
+			frequency = <2400>;
+		};
+	};
+
 	named-gpios {
 		compatible = "named-gpios";
 
@@ -467,3 +492,23 @@
 &cros_kb_raw {
 	status = "okay";
 };
+
+/* Green LED */
+&pwm0 {
+	status = "okay";
+};
+
+/* Red LED */
+&pwm1 {
+	status = "okay";
+};
+
+/* Blue LED */
+&pwm2 {
+	status = "okay";
+};
+
+/* Side selection LED */
+&pwm7 {
+	status = "okay";
+};
diff --git a/zephyr/projects/volteer/prj.conf b/zephyr/projects/volteer/prj.conf
index 8a23041b54..b113b9af8c 100644
--- a/zephyr/projects/volteer/prj.conf
+++ b/zephyr/projects/volteer/prj.conf
@@ -35,6 +35,10 @@ CONFIG_PLATFORM_EC_POWERSEQ=y
 CONFIG_PLATFORM_EC_POWERSEQ_RTC_RESET=y
 CONFIG_PLATFORM_EC_POWERSEQ_S0IX=y
 
+# PWM
+CONFIG_PWM=y
+CONFIG_PLATFORM_EC_PWM=y
+
 # Miscellaneous tasks
 CONFIG_HAS_TASK_KEYPROTO=y
 CONFIG_HAS_TASK_POWERBTN=y
diff --git a/zephyr/shim/include/config_chip.h b/zephyr/shim/include/config_chip.h
index ce9063d4f9..5da5f63a72 100644
--- a/zephyr/shim/include/config_chip.h
+++ b/zephyr/shim/include/config_chip.h
@@ -252,6 +252,11 @@ enum battery_type {
 #define CONFIG_FAKE_SHMEM
 #endif
 
+#undef CONFIG_PWM
+#ifdef CONFIG_PLATFORM_EC_PWM
+#define CONFIG_PWM
+#endif
+
 #undef CONFIG_CMD_SHMEM
 #ifdef CONFIG_PLATFORM_EC_CONSOLE_CMD_SHMEM
 #define CONFIG_CMD_SHMEM
diff --git a/zephyr/shim/include/pwm/pwm.h b/zephyr/shim/include/pwm/pwm.h
new file mode 100644
index 0000000000..38720abb39
--- /dev/null
+++ b/zephyr/shim/include/pwm/pwm.h
@@ -0,0 +1,24 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef ZEPHYR_SHIM_INCLUDE_PWM_PWM_H_
+#define ZEPHYR_SHIM_INCLUDE_PWM_PWM_H_
+
+#include <device.h>
+#include <devicetree.h>
+
+#if DT_NODE_EXISTS(DT_PATH(named_pwms))
+
+#define PWM_CHANNEL(id) DT_CAT(PWM_, id)
+#define PWM_CHANNEL_WITH_COMMA(id) PWM_CHANNEL(id),
+
+enum pwm_channel {
+	DT_FOREACH_CHILD(DT_PATH(named_pwms), PWM_CHANNEL_WITH_COMMA)
+		PWM_CH_COUNT,
+};
+
+#endif /* named_pwms */
+
+#endif /* ZEPHYR_SHIM_INCLUDE_PWM_PWM_H_ */
diff --git a/zephyr/shim/src/CMakeLists.txt b/zephyr/shim/src/CMakeLists.txt
index 6512938e56..1a4a75025e 100644
--- a/zephyr/shim/src/CMakeLists.txt
+++ b/zephyr/shim/src/CMakeLists.txt
@@ -15,6 +15,7 @@ zephyr_sources_ifdef(CONFIG_PLATFORM_EC_HOOKS       hooks.c)
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_HOSTCMD     host_command.c)
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_MKBP_EVENT  mkbp_event.c)
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_PANIC       panic.c)
+zephyr_sources_ifdef(CONFIG_PLATFORM_EC_PWM         pwm.c)
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_TIMER       hwtimer.c)
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_I2C         i2c.c)
 zephyr_sources_ifdef(CONFIG_CROS_EC                 system.c)
diff --git a/zephyr/shim/src/pwm.c b/zephyr/shim/src/pwm.c
new file mode 100644
index 0000000000..a9466684d6
--- /dev/null
+++ b/zephyr/shim/src/pwm.c
@@ -0,0 +1,187 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <device.h>
+#include <devicetree.h>
+#include <drivers/pwm.h>
+#include <logging/log.h>
+
+#include "common.h"
+#include "console.h"
+#include "ec_commands.h"
+#include "pwm.h"
+#include "util.h"
+
+#include "pwm/pwm.h"
+
+LOG_MODULE_REGISTER(pwm_shim, LOG_LEVEL_ERR);
+
+#define USECS_PER_SEC 1000000
+
+/*
+ * Initialize the device bindings in pwm_channels.
+ * This macro is called from within DT_FOREACH_CHILD
+ */
+#define INIT_DEV_BINDING(id) {                                              \
+		pwm_configs[PWM_CHANNEL(id)].name = DT_LABEL(id);           \
+		pwm_configs[PWM_CHANNEL(id)].dev = device_get_binding(      \
+			DT_PROP_BY_PHANDLE(id, pwms, label));               \
+		pwm_configs[PWM_CHANNEL(id)].pin = DT_PWMS_CHANNEL(id);     \
+		pwm_configs[PWM_CHANNEL(id)].flags = DT_PWMS_FLAGS(id);     \
+		pwm_configs[PWM_CHANNEL(id)].freq = DT_PROP(id, frequency); \
+	}
+
+struct pwm_config {
+	/* Name */
+	const char *name;
+	/* PWM pin */
+	uint32_t pin;
+	/* PWM channel flags. See dt-bindings/pwm/pwm.h */
+	pwm_flags_t flags;
+	/* PWM operating frequency. Configured by the devicetree */
+	uint32_t freq;
+
+	/* PWM period in microseconds. Automatically set to 1/frequency */
+	uint32_t period_us;
+	/* PWM pulse in microseconds. Set by pwm_set_raw_duty */
+	uint32_t pulse_us;
+	/* Saves whether the PWM channel is currently enabled */
+	bool enabled;
+
+	/* Runtime device for PWM */
+	const struct device *dev;
+};
+
+static struct pwm_config pwm_configs[PWM_CH_COUNT];
+
+static int init_pwms(const struct device *unused)
+{
+	struct pwm_config *pwm;
+	int rv = 0;
+
+	ARG_UNUSED(unused);
+
+	/* Initialize PWM data from the device tree */
+	DT_FOREACH_CHILD(DT_PATH(named_pwms), INIT_DEV_BINDING)
+
+	/* Read the PWM operating frequency, set by the chip driver */
+	for (size_t i = 0; i < PWM_CH_COUNT; ++i) {
+		pwm = &pwm_configs[i];
+
+		if (pwm->dev == NULL) {
+			LOG_ERR("Not found (%s)", pwm->name);
+			rv = -ENODEV;
+			continue;
+		}
+
+		/*
+		 * TODO - check that devicetree frequency is less than 1/2
+		 * max frequency from the chip driver.
+		 */
+		pwm->period_us = USECS_PER_SEC / pwm->freq;
+	}
+
+	return rv;
+}
+SYS_INIT(init_pwms, PRE_KERNEL_1, 50);
+
+static struct pwm_config* pwm_lookup(enum pwm_channel ch)
+{
+	__ASSERT(ch < ARRAY_SIZE(pwm_configs), "Invalid PWM channel %d", ch);
+
+	return &pwm_configs[ch];
+}
+
+void pwm_enable(enum pwm_channel ch, int enabled)
+{
+	struct pwm_config *pwm;
+	uint32_t pulse_us;
+	int rv;
+
+	pwm = pwm_lookup(ch);
+	pwm->enabled = enabled;
+
+	/*
+	 * The Zephyr API doesn't provide explicit enable and disable
+	 * commands. However, setting the pulse width to zero disables
+	 * the PWM.
+	 */
+	if (enabled)
+		pulse_us = pwm->pulse_us;
+	else
+		pulse_us = 0;
+
+	rv = pwm_pin_set_usec(pwm->dev, pwm->pin, pwm->period_us, pulse_us,
+			      pwm->flags);
+
+	if (rv)
+		LOG_ERR("pwm_pin_set_usec() failed %s (%d)", pwm->name, rv);
+}
+
+int pwm_get_enabled(enum pwm_channel ch)
+{
+	struct pwm_config *pwm;
+
+	pwm = pwm_lookup(ch);
+	return pwm->enabled;
+}
+
+void pwm_set_raw_duty(enum pwm_channel ch, uint16_t duty)
+{
+	struct pwm_config *pwm;
+	int rv;
+
+	pwm = pwm_lookup(ch);
+
+	pwm->pulse_us =
+		DIV_ROUND_NEAREST(pwm->period_us * duty, EC_PWM_MAX_DUTY);
+
+	LOG_DBG("PWM %s set raw duty (0x%04x), pulse %d", pwm->name, duty,
+		pwm->pulse_us);
+
+	rv = pwm_pin_set_usec(pwm->dev, pwm->pin, pwm->period_us, pwm->pulse_us,
+			      pwm->flags);
+
+	if (rv)
+		LOG_ERR("pwm_pin_set_usec() failed %s (%d)", pwm->name, rv);
+}
+
+uint16_t pwm_get_raw_duty(enum pwm_channel ch)
+{
+	struct pwm_config *pwm;
+
+	pwm = pwm_lookup(ch);
+
+	return DIV_ROUND_NEAREST(pwm->pulse_us * EC_PWM_MAX_DUTY,
+				 pwm->period_us);
+}
+
+void pwm_set_duty(enum pwm_channel ch, int percent)
+{
+	struct pwm_config *pwm;
+	int rv;
+
+	pwm = pwm_lookup(ch);
+
+	pwm->pulse_us = DIV_ROUND_NEAREST(pwm->period_us * percent, 100);
+
+	LOG_DBG("PWM %s set percent (%d), pulse %d", pwm->name, percent,
+		pwm->pulse_us);
+
+	rv = pwm_pin_set_usec(pwm->dev, pwm->pin, pwm->period_us, pwm->pulse_us,
+			      pwm->flags);
+
+	if (rv)
+		LOG_ERR("pwm_pin_set_usec() failed %s (%d)", pwm->name, rv);
+}
+
+int pwm_get_duty(enum pwm_channel ch)
+{
+	struct pwm_config *pwm;
+
+	pwm = pwm_lookup(ch);
+
+	return DIV_ROUND_NEAREST(pwm->pulse_us * 100, pwm->period_us);
+}