[U-Boot] [PATCH v2 08/19] tegra: Add support for PWFM

Simon Glass
2012-06-13T16:19:44Z

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>
---

arch/arm/cpu/armv7/tegra2/Makefile | 1 +
arch/arm/cpu/armv7/tegra2/pwfm.c | 40 +++++++++++++++++++++++
arch/arm/include/asm/arch-tegra2/pwfm.h | 54 +++++++++++++++++++++++++++++++
3 files changed, 95 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/cpu/armv7/tegra2/pwfm.c
create mode 100644 arch/arm/include/asm/arch-tegra2/pwfm.h

diff --git a/arch/arm/cpu/armv7/tegra2/Makefile b/arch/arm/cpu/armv7/tegra2/Makefile
index 08c4137..9779e9e 100644
--- a/arch/arm/cpu/armv7/tegra2/Makefile
+++ b/arch/arm/cpu/armv7/tegra2/Makefile
@@ -39,6 +39,7 @@ COBJS-$(CONFIG_TEGRA_CLOCK_SCALING) += emc.o
COBJS-$(CONFIG_TEGRA_PMU) += pmu.o
COBJS-$(CONFIG_USB_EHCI_TEGRA) += usb.o
COBJS-$(CONFIG_TEGRA2_LP0) += crypto.o warmboot.o warmboot_avp.o
+COBJS-$(CONFIG_VIDEO_TEGRA) += pwfm.o

COBJS := $(COBJS-y)
SRCS := $(SOBJS:.o=.S) $(COBJS:.o=.c)
diff --git a/arch/arm/cpu/armv7/tegra2/pwfm.c b/arch/arm/cpu/armv7/tegra2/pwfm.c
new file mode 100644
index 0000000..cdb0cbe
--- /dev/null
+++ b/arch/arm/cpu/armv7/tegra2/pwfm.c
@@ -0,0 +1,40 @@
+/*
+ * Tegra2 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
+ */
+
+#include <asm/io.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/pwfm.h>
+
+void pwfm_enable(struct pwfm_ctlr *pwfm, int rate, int pulse_width,
+ int freq_divider)
+{
+ u32 reg;
+
+ /* TODO: Can we use clock_adjust_periph_pll_div() here? */
+ clock_start_periph_pll(PERIPH_ID_PWM, CLOCK_ID_SFROM32KHZ, rate);
+
+ reg = PWFM_ENABLE_MASK;
+ reg |= pulse_width << PWFM_WIDTH_SHIFT;
+ reg |= freq_divider << PWFM_DIVIDER_SHIFT;
+ writel(reg, &pwfm->control);
+}
diff --git a/arch/arm/include/asm/arch-tegra2/pwfm.h b/arch/arm/include/asm/arch-tegra2/pwfm.h
new file mode 100644
index 0000000..69e2edd
--- /dev/null
+++ b/arch/arm/include/asm/arch-tegra2/pwfm.h
@@ -0,0 +1,54 @@
+/*
+ * 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_PWFM_H
+#define __ASM_ARCH_TEGRA_PWFM_H
+
+/* This is a single PWFM channel */
+struct pwfm_ctlr {
+ uint control; /* Control register */
+};
+
+/* PWM_CONTROLLER_PWM_CSR_0/1/2/3_0 */
+#define PWFM_ENABLE_SHIFT 31
+#define PWFM_ENABLE_MASK (0x1 << PWFM_ENABLE_SHIFT)
+
+#define PWFM_WIDTH_SHIFT 16
+#define PWFM_WIDTH_MASK (0x7FFF << PWFM_WIDTH_SHIFT)
+
+#define PWFM_DIVIDER_SHIFT 0
+#define PWFM_DIVIDER_MASK (0x1FFF << PWFM_DIVIDER_SHIFT)
+
+/**
+ * Program the PWFM with the given parameters.
+ *
+ * @param pwfm Pointer to PWFM register
+ * @param rate Clock rate to use for PWFM
+ * @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 pwfm_enable(struct pwfm_ctlr *pwfm, int rate, int pulse_width,
+ int freq_divider);
+
+#endif /* __ASM_ARCH_TEGRA_PWFM_H */
--
1.7.7.3