1727339590
The CLOCKSOURCE_OF_DECLARE macro is used widely for the timers to declare the clocksource at early stage. However, this macro is also used to initialize the clockevent if any, or the clockevent only. It was originally suggested to declare another macro to initialize a clockevent, so in order to separate the two entities even they belong to the same IP. This was not accepted because of the impact on the DT where splitting a clocksource/clockevent definition does not make sense as it is a Linux concept not a hardware description. On the other side, the clocksource has not interrupt declared while the clockevent has, so it is easy from the driver to know if the description is for a clockevent or a clocksource, IOW it could be implemented at the driver level. So instead of dealing with a named clocksource macro, let's use a more generic one: TIMER_OF_DECLARE. The patch has not functional changes. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Heiko Stuebner <heiko@sntech.de> Acked-by: Neil Armstrong <narmstrong@baylibre.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Matthias Brugger <matthias.bgg@gmail.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
136 lines
3 KiB
C
136 lines
3 KiB
C
/*
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* Clocksource using the Low Power Timer found in the Low Power Controller (LPC)
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*
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* Copyright (C) 2015 STMicroelectronics – All Rights Reserved
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*
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* Author(s): Francesco Virlinzi <francesco.virlinzi@st.com>
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* Ajit Pal Singh <ajitpal.singh@st.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/clk.h>
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#include <linux/clocksource.h>
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#include <linux/init.h>
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#include <linux/of_address.h>
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#include <linux/sched_clock.h>
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#include <linux/slab.h>
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#include <dt-bindings/mfd/st-lpc.h>
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/* Low Power Timer */
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#define LPC_LPT_LSB_OFF 0x400
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#define LPC_LPT_MSB_OFF 0x404
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#define LPC_LPT_START_OFF 0x408
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static struct st_clksrc_ddata {
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struct clk *clk;
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void __iomem *base;
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} ddata;
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static void __init st_clksrc_reset(void)
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{
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writel_relaxed(0, ddata.base + LPC_LPT_START_OFF);
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writel_relaxed(0, ddata.base + LPC_LPT_MSB_OFF);
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writel_relaxed(0, ddata.base + LPC_LPT_LSB_OFF);
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writel_relaxed(1, ddata.base + LPC_LPT_START_OFF);
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}
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static u64 notrace st_clksrc_sched_clock_read(void)
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{
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return (u64)readl_relaxed(ddata.base + LPC_LPT_LSB_OFF);
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}
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static int __init st_clksrc_init(void)
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{
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unsigned long rate;
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int ret;
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st_clksrc_reset();
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rate = clk_get_rate(ddata.clk);
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sched_clock_register(st_clksrc_sched_clock_read, 32, rate);
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ret = clocksource_mmio_init(ddata.base + LPC_LPT_LSB_OFF,
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"clksrc-st-lpc", rate, 300, 32,
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clocksource_mmio_readl_up);
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if (ret) {
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pr_err("clksrc-st-lpc: Failed to register clocksource\n");
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return ret;
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}
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return 0;
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}
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static int __init st_clksrc_setup_clk(struct device_node *np)
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{
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struct clk *clk;
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clk = of_clk_get(np, 0);
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if (IS_ERR(clk)) {
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pr_err("clksrc-st-lpc: Failed to get LPC clock\n");
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return PTR_ERR(clk);
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}
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if (clk_prepare_enable(clk)) {
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pr_err("clksrc-st-lpc: Failed to enable LPC clock\n");
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return -EINVAL;
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}
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if (!clk_get_rate(clk)) {
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pr_err("clksrc-st-lpc: Failed to get LPC clock rate\n");
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clk_disable_unprepare(clk);
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return -EINVAL;
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}
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ddata.clk = clk;
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return 0;
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}
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static int __init st_clksrc_of_register(struct device_node *np)
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{
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int ret;
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uint32_t mode;
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ret = of_property_read_u32(np, "st,lpc-mode", &mode);
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if (ret) {
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pr_err("clksrc-st-lpc: An LPC mode must be provided\n");
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return ret;
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}
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/* LPC can either run as a Clocksource or in RTC or WDT mode */
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if (mode != ST_LPC_MODE_CLKSRC)
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return 0;
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ddata.base = of_iomap(np, 0);
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if (!ddata.base) {
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pr_err("clksrc-st-lpc: Unable to map iomem\n");
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return -ENXIO;
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}
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ret = st_clksrc_setup_clk(np);
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if (ret) {
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iounmap(ddata.base);
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return ret;
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}
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ret = st_clksrc_init();
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if (ret) {
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clk_disable_unprepare(ddata.clk);
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clk_put(ddata.clk);
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iounmap(ddata.base);
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return ret;
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}
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pr_info("clksrc-st-lpc: clocksource initialised - running @ %luHz\n",
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clk_get_rate(ddata.clk));
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return ret;
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}
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TIMER_OF_DECLARE(ddata, "st,stih407-lpc", st_clksrc_of_register);
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