diff options
Diffstat (limited to 'drivers/clocksource/timer-pistachio.c')
| -rw-r--r-- | drivers/clocksource/timer-pistachio.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-pistachio.c b/drivers/clocksource/timer-pistachio.c new file mode 100644 index 000000000000..a2dd85d0c1d7 --- /dev/null +++ b/drivers/clocksource/timer-pistachio.c @@ -0,0 +1,218 @@ +/* + * 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 u64 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 (u64)~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 int __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 -ENXIO; + } + + periph_regs = syscon_regmap_lookup_by_phandle(node, "img,cr-periph"); + if (IS_ERR(periph_regs)) { + pr_err("cannot get peripheral regmap (%ld)\n", + PTR_ERR(periph_regs)); + return PTR_ERR(periph_regs); + } + + /* Switch to using the fast counter clock */ + ret = regmap_update_bits(periph_regs, PERIP_TIMER_CONTROL, + 0xf, 0x0); + if (ret) + return ret; + + sys_clk = of_clk_get_by_name(node, "sys"); + if (IS_ERR(sys_clk)) { + pr_err("clock get failed (%ld)\n", PTR_ERR(sys_clk)); + return PTR_ERR(sys_clk); + } + + 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 PTR_ERR(fast_clk); + } + + ret = clk_prepare_enable(sys_clk); + if (ret < 0) { + pr_err("failed to enable clock (%d)\n", ret); + return ret; + } + + ret = clk_prepare_enable(fast_clk); + if (ret < 0) { + pr_err("failed to enable clock (%d)\n", ret); + clk_disable_unprepare(sys_clk); + return ret; + } + + 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); + return clocksource_register_hz(&pcs_gpt.cs, rate); +} +TIMER_OF_DECLARE(pistachio_gptimer, "img,pistachio-gptimer", + pistachio_clksrc_of_init); |