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 */