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84583983c3
The Pistachio SoC provides four general purpose timers, and allow to implement a clocksource driver. This driver can be used as a replacement for the MIPS GIC and MIPS R4K clocksources and sched clocks, which are clocked from the CPU clock. Given the general purpose timers are clocked from an independent clock, this new clocksource driver will be useful to introduce CPUFreq support for Pistachio machines. Signed-off-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com> Signed-off-by: Govindraj Raja <govindraj.raja@imgtec.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: devicetree@vger.kernel.org Cc: Andrew Bresticker <abrestic@chromium.org> Cc: James Hartley <James.Hartley@imgtec.com> Cc: Damien Horsley <Damien.Horsley@imgtec.com> Cc: James Hogan <James.Hogan@imgtec.com> Cc: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> Cc: Ezequiel Garcia <ezequiel.garcia@imgtec.com> Patchwork: https://patchwork.linux-mips.org/patch/10899/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
218 lines
5.5 KiB
C
218 lines
5.5 KiB
C
/*
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* Pistachio clocksource based on general-purpose timers
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*
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* Copyright (C) 2015 Imagination Technologies
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#define pr_fmt(fmt) "%s: " fmt, __func__
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#include <linux/clk.h>
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/mfd/syscon.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#include <linux/sched_clock.h>
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#include <linux/time.h>
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/* Top level reg */
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#define CR_TIMER_CTRL_CFG 0x00
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#define TIMER_ME_GLOBAL BIT(0)
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#define CR_TIMER_REV 0x10
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/* Timer specific registers */
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#define TIMER_CFG 0x20
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#define TIMER_ME_LOCAL BIT(0)
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#define TIMER_RELOAD_VALUE 0x24
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#define TIMER_CURRENT_VALUE 0x28
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#define TIMER_CURRENT_OVERFLOW_VALUE 0x2C
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#define TIMER_IRQ_STATUS 0x30
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#define TIMER_IRQ_CLEAR 0x34
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#define TIMER_IRQ_MASK 0x38
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#define PERIP_TIMER_CONTROL 0x90
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/* Timer specific configuration Values */
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#define RELOAD_VALUE 0xffffffff
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struct pistachio_clocksource {
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void __iomem *base;
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raw_spinlock_t lock;
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struct clocksource cs;
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};
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static struct pistachio_clocksource pcs_gpt;
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#define to_pistachio_clocksource(cs) \
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container_of(cs, struct pistachio_clocksource, cs)
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static inline u32 gpt_readl(void __iomem *base, u32 offset, u32 gpt_id)
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{
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return readl(base + 0x20 * gpt_id + offset);
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}
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static inline void gpt_writel(void __iomem *base, u32 value, u32 offset,
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u32 gpt_id)
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{
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writel(value, base + 0x20 * gpt_id + offset);
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}
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static cycle_t pistachio_clocksource_read_cycles(struct clocksource *cs)
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{
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struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
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u32 counter, overflw;
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unsigned long flags;
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/*
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* The counter value is only refreshed after the overflow value is read.
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* And they must be read in strict order, hence raw spin lock added.
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*/
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raw_spin_lock_irqsave(&pcs->lock, flags);
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overflw = gpt_readl(pcs->base, TIMER_CURRENT_OVERFLOW_VALUE, 0);
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counter = gpt_readl(pcs->base, TIMER_CURRENT_VALUE, 0);
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raw_spin_unlock_irqrestore(&pcs->lock, flags);
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return ~(cycle_t)counter;
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}
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static u64 notrace pistachio_read_sched_clock(void)
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{
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return pistachio_clocksource_read_cycles(&pcs_gpt.cs);
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}
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static void pistachio_clksrc_set_mode(struct clocksource *cs, int timeridx,
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int enable)
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{
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struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
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u32 val;
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val = gpt_readl(pcs->base, TIMER_CFG, timeridx);
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if (enable)
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val |= TIMER_ME_LOCAL;
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else
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val &= ~TIMER_ME_LOCAL;
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gpt_writel(pcs->base, val, TIMER_CFG, timeridx);
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}
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static void pistachio_clksrc_enable(struct clocksource *cs, int timeridx)
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{
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struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
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/* Disable GPT local before loading reload value */
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pistachio_clksrc_set_mode(cs, timeridx, false);
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gpt_writel(pcs->base, RELOAD_VALUE, TIMER_RELOAD_VALUE, timeridx);
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pistachio_clksrc_set_mode(cs, timeridx, true);
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}
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static void pistachio_clksrc_disable(struct clocksource *cs, int timeridx)
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{
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/* Disable GPT local */
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pistachio_clksrc_set_mode(cs, timeridx, false);
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}
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static int pistachio_clocksource_enable(struct clocksource *cs)
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{
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pistachio_clksrc_enable(cs, 0);
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return 0;
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}
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static void pistachio_clocksource_disable(struct clocksource *cs)
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{
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pistachio_clksrc_disable(cs, 0);
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}
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/* Desirable clock source for pistachio platform */
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static struct pistachio_clocksource pcs_gpt = {
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.cs = {
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.name = "gptimer",
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.rating = 300,
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.enable = pistachio_clocksource_enable,
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.disable = pistachio_clocksource_disable,
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.read = pistachio_clocksource_read_cycles,
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.mask = CLOCKSOURCE_MASK(32),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS |
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CLOCK_SOURCE_SUSPEND_NONSTOP,
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},
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};
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static void __init pistachio_clksrc_of_init(struct device_node *node)
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{
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struct clk *sys_clk, *fast_clk;
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struct regmap *periph_regs;
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unsigned long rate;
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int ret;
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pcs_gpt.base = of_iomap(node, 0);
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if (!pcs_gpt.base) {
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pr_err("cannot iomap\n");
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return;
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}
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periph_regs = syscon_regmap_lookup_by_phandle(node, "img,cr-periph");
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if (IS_ERR(periph_regs)) {
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pr_err("cannot get peripheral regmap (%lu)\n",
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PTR_ERR(periph_regs));
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return;
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}
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/* Switch to using the fast counter clock */
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ret = regmap_update_bits(periph_regs, PERIP_TIMER_CONTROL,
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0xf, 0x0);
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if (ret)
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return;
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sys_clk = of_clk_get_by_name(node, "sys");
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if (IS_ERR(sys_clk)) {
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pr_err("clock get failed (%lu)\n", PTR_ERR(sys_clk));
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return;
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}
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fast_clk = of_clk_get_by_name(node, "fast");
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if (IS_ERR(fast_clk)) {
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pr_err("clock get failed (%lu)\n", PTR_ERR(fast_clk));
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return;
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}
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ret = clk_prepare_enable(sys_clk);
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if (ret < 0) {
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pr_err("failed to enable clock (%d)\n", ret);
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return;
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}
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ret = clk_prepare_enable(fast_clk);
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if (ret < 0) {
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pr_err("failed to enable clock (%d)\n", ret);
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clk_disable_unprepare(sys_clk);
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return;
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}
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rate = clk_get_rate(fast_clk);
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/* Disable irq's for clocksource usage */
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gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 0);
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gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 1);
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gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 2);
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gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 3);
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/* Enable timer block */
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writel(TIMER_ME_GLOBAL, pcs_gpt.base);
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raw_spin_lock_init(&pcs_gpt.lock);
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sched_clock_register(pistachio_read_sched_clock, 32, rate);
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clocksource_register_hz(&pcs_gpt.cs, rate);
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}
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CLOCKSOURCE_OF_DECLARE(pistachio_gptimer, "img,pistachio-gptimer",
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pistachio_clksrc_of_init);
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