tegra: Add support for PWM

The pulse width/frequency modulation peripheral supports generating
a repeating pulse. It is useful for controlling LCD brightness.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 75 insertions, 0 deletions

diff --git a/arch/arm/include/asm/arch-tegra20/pwm.h b/arch/arm/include/asm/arch-tegra20/pwm.h
new file mode 100644
index 0000000000..9e03837ccb
--- /dev/null
+++ b/arch/arm/include/asm/arch-tegra20/pwm.h
@@ -0,0 +1,75 @@
+/*
+ * Tegra pulse width frequency modulator definitions
+ *
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef __ASM_ARCH_TEGRA_PWM_H
+#define __ASM_ARCH_TEGRA_PWM_H
+
+/* This is a single PWM channel */
+struct pwm_ctlr {
+	uint control;		/* Control register */
+	uint reserved[3];	/* Space space */
+};
+
+#define PWM_NUM_CHANNELS	4
+
+/* PWM_CONTROLLER_PWM_CSR_0/1/2/3_0 */
+#define PWM_ENABLE_SHIFT	31
+#define PWM_ENABLE_MASK	(0x1 << PWM_ENABLE_SHIFT)
+
+#define PWM_WIDTH_SHIFT	16
+#define PWM_WIDTH_MASK		(0x7FFF << PWM_WIDTH_SHIFT)
+
+#define PWM_DIVIDER_SHIFT	0
+#define PWM_DIVIDER_MASK	(0x1FFF << PWM_DIVIDER_SHIFT)
+
+/**
+ * Program the PWM with the given parameters.
+ *
+ * @param channel	PWM channel to update
+ * @param rate		Clock rate to use for PWM
+ * @param pulse_width	high pulse width: 0=always low, 1=1/256 pulse high,
+ *			n = n/256 pulse high
+ * @param freq_divider	frequency divider value (1 to use rate as is)
+ */
+void pwm_enable(unsigned channel, int rate, int pulse_width, int freq_divider);
+
+/**
+ * Request a pwm channel as referenced by a device tree node.
+ *
+ * This channel can then be passed to pwm_enable().
+ *
+ * @param blob		Device tree blob
+ * @param node		Node containing reference to pwm
+ * @param prop_name	Property name of pwm reference
+ * @return channel number, if ok, else -1
+ */
+int pwm_request(const void *blob, int node, const char *prop_name);
+
+/**
+ * Set up the pwm controller, by looking it up in the fdt.
+ *
+ * @return 0 if ok, -1 if the device tree node was not found or invalid.
+ */
+int pwm_init(const void *blob);
+
+#endif	/* __ASM_ARCH_TEGRA_PWM_H */