Refactor PWM module

This unifies the PWM module interface for LM4 and STM32. Now PWM
channels are defined in board.h/board.c. Instead of calling functions
named pwm_set_fan_duty(x), one can now use pwm_set_duty(PWM_CH_FAN, x),
which prevents additional functions added when we have a new PWM
channel.

BUG=chrome-os-partner:18343
TEST=Limit input current on Spring.
TEST=Check power LED in S0/S3/S5 on Snow.
TEST=Check keyboard backlight functionality on Link.
TEST=Check fan speed control/detecting on Link.
BRANCH=None

Change-Id: Ibac4d79f72e65c94776d503558a7592f7db859dc
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/64450
Reviewed-by: Randall Spangler <rspangler@chromium.org>

1 files changed, 154 insertions, 0 deletions

diff --git a/chip/stm32/pwm.c b/chip/stm32/pwm.c
new file mode 100644
index 0000000000..73db55334f
--- /dev/null
+++ b/chip/stm32/pwm.c
@@ -0,0 +1,154 @@
+/* Copyright (c) 2013 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.
+ */
+
+/* PWM control module for STM32 */
+
+#include "clock.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "hwtimer.h"
+#include "pwm.h"
+#include "pwm_data.h"
+#include "registers.h"
+#include "util.h"
+
+static int using_pwm[PWM_CH_COUNT];
+
+void pwm_set_duty(enum pwm_channel ch, int percent)
+{
+	const struct pwm_t *pwm = pwm_channels + ch;
+	timer_ctlr_t *tim = (timer_ctlr_t *)(pwm->tim.base);
+
+	ASSERT((percent >= 0) && (percent <= 100));
+	tim->ccr[pwm->channel] = percent;
+}
+
+int pwm_get_duty(enum pwm_channel ch)
+{
+	const struct pwm_t *pwm = pwm_channels + ch;
+	timer_ctlr_t *tim = (timer_ctlr_t *)(pwm->tim.base);
+	return tim->ccr[pwm->channel];
+}
+
+static void pwm_configure(enum pwm_channel ch)
+{
+	const struct pwm_t *pwm = pwm_channels + ch;
+	const struct gpio_info *gpio = gpio_list + pwm->pin;
+	timer_ctlr_t *tim = (timer_ctlr_t *)(pwm->tim.base);
+	volatile unsigned *ccmr = NULL;
+#ifdef CHIP_FAMILY_stm32f
+	int mask = gpio->mask;
+	volatile uint32_t *gpio_cr = NULL;
+	uint32_t val;
+#endif
+
+	if (using_pwm[ch])
+		return;
+
+#ifdef CHIP_FAMILY_stm32f
+	if (mask < 0x100) {
+		gpio_cr = &STM32_GPIO_CRL(gpio->port);
+	} else {
+		gpio_cr = &STM32_GPIO_CRH(gpio->port);
+		mask >>= 8;
+	}
+
+	/* Expand mask from 8-bit to 32-bit */
+	mask = mask * mask;
+	mask = mask * mask;
+
+	/* Set alternate function */
+	val = *gpio_cr & ~(mask * 0xf);
+	val |= mask * 0x9;
+	*gpio_cr = val;
+#else /* stm32l */
+	gpio_set_alternate_function(gpio->port, gpio->mask,
+				    GPIO_ALT_TIM(pwm->tim.id));
+#endif
+
+	/* Enable timer */
+	__hw_timer_enable_clock(pwm->tim.id, 1);
+
+	/* Disable counter during setup */
+	tim->cr1 = 0x0000;
+
+	/*
+	 * CPU clock / PSC determines how fast the counter operates.
+	 * ARR determines the wave period, CCRn determines duty cycle.
+	 * Thus, frequency = cpu_freq / PSC / ARR. so:
+	 *
+	 *     frequency = cpu_freq / (cpu_freq/10000) / 100 = 100 Hz.
+	 */
+	tim->psc = clock_get_freq() / 10000;
+	tim->arr = 100;
+
+	if (pwm->channel <= 2) /* Channel ID starts from 1 */
+		ccmr = &tim->ccmr1;
+	else
+		ccmr = &tim->ccmr2;
+
+	/* Output, PWM mode 1, preload enable */
+	if (pwm->channel & 0x1)
+		*ccmr = (6 << 4) | (1 << 3);
+	else
+		*ccmr = (6 << 12) | (1 << 11);
+
+	/* Output enable. Set active high/low. */
+	if (pwm->flags & PWM_CONFIG_ACTIVE_LOW)
+		tim->ccer = 3 << (pwm->channel * 4 - 4);
+	else
+		tim->ccer = 1 << (pwm->channel * 4 - 4);
+
+	/* Generate update event to force loading of shadow registers */
+	tim->egr |= 1;
+
+	/* Enable auto-reload preload, start counting */
+	tim->cr1 |= (1 << 7) | (1 << 0);
+
+	using_pwm[ch] = 1;
+}
+
+static void pwm_disable(enum pwm_channel ch)
+{
+	const struct pwm_t *pwm = pwm_channels + ch;
+	timer_ctlr_t *tim = (timer_ctlr_t *)(pwm->tim.base);
+
+	if (using_pwm[ch] == 0)
+		return;
+
+	/* Disable counter */
+	tim->cr1 &= ~0x1;
+
+	/* Disable timer clock */
+	__hw_timer_enable_clock(pwm->tim.id, 0);
+
+	using_pwm[ch] = 0;
+}
+
+void pwm_enable(enum pwm_channel ch, int enabled)
+{
+	if (enabled)
+		pwm_configure(ch);
+	else
+		pwm_disable(ch);
+}
+
+static void pwm_reconfigure(enum pwm_channel ch)
+{
+	using_pwm[ch] = 0;
+	pwm_configure(ch);
+}
+
+/**
+ * Handle clock frequency change
+ */
+static void pwm_freq_change(void)
+{
+	int i;
+	for (i = 0; i < PWM_CH_COUNT; ++i)
+		if (using_pwm[i])
+			pwm_reconfigure(i);
+}
+DECLARE_HOOK(HOOK_FREQ_CHANGE, pwm_freq_change, HOOK_PRIO_DEFAULT);