clocksource: sti: Provide support for the ST LPC Clocksource IP (70bef01c) · Commits · 戴 / test

drivers/clocksource/Kconfig

+8 −0

Original line number	Diff line number	Diff line
		@@ -293,4 +293,12 @@ config CLKSRC_IMX_GPT
		depends on ARM && CLKDEV_LOOKUP
		select CLKSRC_MMIO

		config CLKSRC_ST_LPC
		bool
		depends on ARCH_STI
		select CLKSRC_OF if OF
		help
		Enable this option to use the Low Power controller timer
		as clocksource.

		endmenu

drivers/clocksource/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -60,3 +60,4 @@ obj-$(CONFIG_ASM9260_TIMER) += asm9260_timer.o
		obj-$(CONFIG_H8300) += h8300_timer8.o
		obj-$(CONFIG_H8300_TMR16) += h8300_timer16.o
		obj-$(CONFIG_H8300_TPU) += h8300_tpu.o
		obj-$(CONFIG_CLKSRC_ST_LPC) += clksrc_st_lpc.o

drivers/clocksource/clksrc_st_lpc.c

0 → 100644

+123 −0

Original line number	Diff line number	Diff line
		/*
		* Clocksource using the Low Power Timer found in the Low Power Controller (LPC)
		*
		* Copyright (C) 2015 STMicroelectronics – All Rights Reserved
		*
		* Author(s): Francesco Virlinzi <francesco.virlinzi@st.com>
		* Ajit Pal Singh <ajitpal.singh@st.com>
		*
		* 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.
		*/

		#include <linux/clk.h>
		#include <linux/clocksource.h>
		#include <linux/init.h>
		#include <linux/of_address.h>
		#include <linux/slab.h>

		#include <dt-bindings/mfd/st-lpc.h>

		/* Low Power Timer */
		#define LPC_LPT_LSB_OFF 0x400
		#define LPC_LPT_MSB_OFF 0x404
		#define LPC_LPT_START_OFF 0x408

		static struct st_clksrc_ddata {
		struct clk *clk;
		void __iomem *base;
		} ddata;

		static void __init st_clksrc_reset(void)
		{
		writel_relaxed(0, ddata.base + LPC_LPT_START_OFF);
		writel_relaxed(0, ddata.base + LPC_LPT_MSB_OFF);
		writel_relaxed(0, ddata.base + LPC_LPT_LSB_OFF);
		writel_relaxed(1, ddata.base + LPC_LPT_START_OFF);
		}

		static int __init st_clksrc_init(void)
		{
		unsigned long rate;
		int ret;

		st_clksrc_reset();

		rate = clk_get_rate(ddata.clk);

		ret = clocksource_mmio_init(ddata.base + LPC_LPT_LSB_OFF,
		"clksrc-st-lpc", rate, 300, 32,
		clocksource_mmio_readl_up);
		if (ret) {
		pr_err("clksrc-st-lpc: Failed to register clocksource\n");
		return ret;
		}

		return 0;
		}

		static int __init st_clksrc_setup_clk(struct device_node *np)
		{
		struct clk *clk;

		clk = of_clk_get(np, 0);
		if (IS_ERR(clk)) {
		pr_err("clksrc-st-lpc: Failed to get LPC clock\n");
		return PTR_ERR(clk);
		}

		if (clk_prepare_enable(clk)) {
		pr_err("clksrc-st-lpc: Failed to enable LPC clock\n");
		return -EINVAL;
		}

		if (!clk_get_rate(clk)) {
		pr_err("clksrc-st-lpc: Failed to get LPC clock rate\n");
		clk_disable_unprepare(clk);
		return -EINVAL;
		}

		ddata.clk = clk;

		return 0;
		}

		static void __init st_clksrc_of_register(struct device_node *np)
		{
		int ret;
		uint32_t mode;

		ret = of_property_read_u32(np, "st,lpc-mode", &mode);
		if (ret) {
		pr_err("clksrc-st-lpc: An LPC mode must be provided\n");
		return;
		}

		/* LPC can either run as a Clocksource or in RTC or WDT mode */
		if (mode != ST_LPC_MODE_CLKSRC)
		return;

		ddata.base = of_iomap(np, 0);
		if (!ddata.base) {
		pr_err("clksrc-st-lpc: Unable to map iomem\n");
		return;
		}

		if (st_clksrc_setup_clk(np)) {
		iounmap(ddata.base);
		return;
		}

		if (st_clksrc_init()) {
		clk_disable_unprepare(ddata.clk);
		clk_put(ddata.clk);
		iounmap(ddata.base);
		return;
		}

		pr_info("clksrc-st-lpc: clocksource initialised - running @ %luHz\n",
		clk_get_rate(ddata.clk));
		}
		CLOCKSOURCE_OF_DECLARE(ddata, "st,stih407-lpc", st_clksrc_of_register);

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