Messages in this thread | | | Date | Mon, 11 May 2015 10:42:47 +0200 | From | Daniel Lezcano <> | Subject | Re: [PATCH 02/12] clocksource: sti: Provide support for the ST LPC Clocksource IP |
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On 05/07/2015 03:38 PM, Lee Jones wrote: > This IP is shared with Watchdog and RTC functionality. Only one of > these IPs can be used at the same 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. > > Signed-off-by: Lee Jones <lee.jones@linaro.org> > --- > drivers/clocksource/Kconfig | 8 +++ > drivers/clocksource/Makefile | 1 + > drivers/clocksource/clksrc_st_lpc.c | 123 ++++++++++++++++++++++++++++++++++++ > 3 files changed, 132 insertions(+) > create mode 100644 drivers/clocksource/clksrc_st_lpc.c > > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > index 68161f7..ac424cf 100644 > --- a/drivers/clocksource/Kconfig > +++ b/drivers/clocksource/Kconfig > @@ -250,4 +250,12 @@ config CLKSRC_PXA > help > This enables OST0 support available on PXA and SA-11x0 > platforms. > + > +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 > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile > index 752d5c7..e08da4d 100644 > --- a/drivers/clocksource/Makefile > +++ b/drivers/clocksource/Makefile > @@ -51,3 +51,4 @@ obj-$(CONFIG_ARCH_INTEGRATOR_AP) += timer-integrator-ap.o > obj-$(CONFIG_CLKSRC_VERSATILE) += versatile.o > obj-$(CONFIG_CLKSRC_MIPS_GIC) += mips-gic-timer.o > obj-$(CONFIG_ASM9260_TIMER) += asm9260_timer.o > +obj-$(CONFIG_CLKSRC_ST_LPC) += clksrc_st_lpc.o > diff --git a/drivers/clocksource/clksrc_st_lpc.c b/drivers/clocksource/clksrc_st_lpc.c > new file mode 100644 > index 0000000..18a7dcd0 > --- /dev/null > +++ b/drivers/clocksource/clksrc_st_lpc.c > @@ -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 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 st_clksrc_setup_clk(struct device_node *np) > +{ > + struct clk *clk; > + int ret; > + > + clk = of_clk_get(np, 0); > + if (IS_ERR(clk)) { > + pr_err("clksrc-st-lpc: Failed to get LPC clock\n"); > + ret = PTR_ERR(clk); > + return ret;
return PTR_ERR(clk);
so you can get rid of the 'int ret' variable.
> + } > + > + 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;
I am confused with this patch description + comment and the patch 1's description.
For the former, I understand the LPC could be in RTC or WDT mode and used as a clocksource (clksrc + rtc / clksrc + wdt), for the latter I understand there are three modes clocksource, rtc and watchdog (mutually exclusive). Could you clarify ?
> + > + 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()) { > + 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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