mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-11 23:03:55 +08:00
clocksource: sti: Provide support for the ST LPC Clocksource IP
This IP is shared with Watchdog and RTC functionality. All 3 of these devices are mutually exclusive from one another i.e. Only 1 IP can be used at any given time. We use the device-driver model combined with a DT 'mode' property to enforce this. The ST LPC Clocksource IP can be used as the system (tick) timer. Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
parent
6f2536141c
commit
70bef01c0f
@ -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
|
||||
|
@ -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
|
||||
|
123
drivers/clocksource/clksrc_st_lpc.c
Normal file
123
drivers/clocksource/clksrc_st_lpc.c
Normal file
@ -0,0 +1,123 @@
|
||||
/*
|
||||
* 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);
|
Loading…
Reference in New Issue
Block a user