--- /dev/null
+/*
+ * Pistachio clocksource based on general-purpose timers
+ *
+ * Copyright (C) 2015 Imagination Technologies
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/clk.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/sched_clock.h>
+#include <linux/time.h>
+
+/* Top level reg */
+#define CR_TIMER_CTRL_CFG 0x00
+#define TIMER_ME_GLOBAL BIT(0)
+#define CR_TIMER_REV 0x10
+
+/* Timer specific registers */
+#define TIMER_CFG 0x20
+#define TIMER_ME_LOCAL BIT(0)
+#define TIMER_RELOAD_VALUE 0x24
+#define TIMER_CURRENT_VALUE 0x28
+#define TIMER_CURRENT_OVERFLOW_VALUE 0x2C
+#define TIMER_IRQ_STATUS 0x30
+#define TIMER_IRQ_CLEAR 0x34
+#define TIMER_IRQ_MASK 0x38
+
+#define PERIP_TIMER_CONTROL 0x90
+
+/* Timer specific configuration Values */
+#define RELOAD_VALUE 0xffffffff
+
+struct pistachio_clocksource {
+ void __iomem *base;
+ raw_spinlock_t lock;
+ struct clocksource cs;
+};
+
+static struct pistachio_clocksource pcs_gpt;
+
+#define to_pistachio_clocksource(cs) \
+ container_of(cs, struct pistachio_clocksource, cs)
+
+static inline u32 gpt_readl(void __iomem *base, u32 offset, u32 gpt_id)
+{
+ return readl(base + 0x20 * gpt_id + offset);
+}
+
+static inline void gpt_writel(void __iomem *base, u32 value, u32 offset,
+ u32 gpt_id)
+{
+ writel(value, base + 0x20 * gpt_id + offset);
+}
+
+static cycle_t notrace
+pistachio_clocksource_read_cycles(struct clocksource *cs)
+{
+ struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
+ u32 counter, overflw;
+ unsigned long flags;
+
+ /*
+ * The counter value is only refreshed after the overflow value is read.
+ * And they must be read in strict order, hence raw spin lock added.
+ */
+
+ raw_spin_lock_irqsave(&pcs->lock, flags);
+ overflw = gpt_readl(pcs->base, TIMER_CURRENT_OVERFLOW_VALUE, 0);
+ counter = gpt_readl(pcs->base, TIMER_CURRENT_VALUE, 0);
+ raw_spin_unlock_irqrestore(&pcs->lock, flags);
+
+ return ~(cycle_t)counter;
+}
+
+static u64 notrace pistachio_read_sched_clock(void)
+{
+ return pistachio_clocksource_read_cycles(&pcs_gpt.cs);
+}
+
+static void pistachio_clksrc_set_mode(struct clocksource *cs, int timeridx,
+ int enable)
+{
+ struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
+ u32 val;
+
+ val = gpt_readl(pcs->base, TIMER_CFG, timeridx);
+ if (enable)
+ val |= TIMER_ME_LOCAL;
+ else
+ val &= ~TIMER_ME_LOCAL;
+
+ gpt_writel(pcs->base, val, TIMER_CFG, timeridx);
+}
+
+static void pistachio_clksrc_enable(struct clocksource *cs, int timeridx)
+{
+ struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
+
+ /* Disable GPT local before loading reload value */
+ pistachio_clksrc_set_mode(cs, timeridx, false);
+ gpt_writel(pcs->base, RELOAD_VALUE, TIMER_RELOAD_VALUE, timeridx);
+ pistachio_clksrc_set_mode(cs, timeridx, true);
+}
+
+static void pistachio_clksrc_disable(struct clocksource *cs, int timeridx)
+{
+ /* Disable GPT local */
+ pistachio_clksrc_set_mode(cs, timeridx, false);
+}
+
+static int pistachio_clocksource_enable(struct clocksource *cs)
+{
+ pistachio_clksrc_enable(cs, 0);
+ return 0;
+}
+
+static void pistachio_clocksource_disable(struct clocksource *cs)
+{
+ pistachio_clksrc_disable(cs, 0);
+}
+
+/* Desirable clock source for pistachio platform */
+static struct pistachio_clocksource pcs_gpt = {
+ .cs = {
+ .name = "gptimer",
+ .rating = 300,
+ .enable = pistachio_clocksource_enable,
+ .disable = pistachio_clocksource_disable,
+ .read = pistachio_clocksource_read_cycles,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS |
+ CLOCK_SOURCE_SUSPEND_NONSTOP,
+ },
+};
+
+static void __init pistachio_clksrc_of_init(struct device_node *node)
+{
+ struct clk *sys_clk, *fast_clk;
+ struct regmap *periph_regs;
+ unsigned long rate;
+ int ret;
+
+ pcs_gpt.base = of_iomap(node, 0);
+ if (!pcs_gpt.base) {
+ pr_err("cannot iomap\n");
+ return;
+ }
+
+ periph_regs = syscon_regmap_lookup_by_phandle(node, "img,cr-periph");
+ if (IS_ERR(periph_regs)) {
+ pr_err("cannot get peripheral regmap (%lu)\n",
+ PTR_ERR(periph_regs));
+ return;
+ }
+
+ /* Switch to using the fast counter clock */
+ ret = regmap_update_bits(periph_regs, PERIP_TIMER_CONTROL,
+ 0xf, 0x0);
+ if (ret)
+ return;
+
+ sys_clk = of_clk_get_by_name(node, "sys");
+ if (IS_ERR(sys_clk)) {
+ pr_err("clock get failed (%lu)\n", PTR_ERR(sys_clk));
+ return;
+ }
+
+ fast_clk = of_clk_get_by_name(node, "fast");
+ if (IS_ERR(fast_clk)) {
+ pr_err("clock get failed (%lu)\n", PTR_ERR(fast_clk));
+ return;
+ }
+
+ ret = clk_prepare_enable(sys_clk);
+ if (ret < 0) {
+ pr_err("failed to enable clock (%d)\n", ret);
+ return;
+ }
+
+ ret = clk_prepare_enable(fast_clk);
+ if (ret < 0) {
+ pr_err("failed to enable clock (%d)\n", ret);
+ clk_disable_unprepare(sys_clk);
+ return;
+ }
+
+ rate = clk_get_rate(fast_clk);
+
+ /* Disable irq's for clocksource usage */
+ gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 0);
+ gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 1);
+ gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 2);
+ gpt_writel(&pcs_gpt.base, 0, TIMER_IRQ_MASK, 3);
+
+ /* Enable timer block */
+ writel(TIMER_ME_GLOBAL, pcs_gpt.base);
+
+ raw_spin_lock_init(&pcs_gpt.lock);
+ sched_clock_register(pistachio_read_sched_clock, 32, rate);
+ clocksource_register_hz(&pcs_gpt.cs, rate);
+}
+CLOCKSOURCE_OF_DECLARE(pistachio_gptimer, "img,pistachio-gptimer",
+ pistachio_clksrc_of_init);
Code Review / kvmfornfv.git / blobdiff