diff options
Diffstat (limited to 'drivers/clocksource/timer-digicolor.c')
| -rw-r--r-- | drivers/clocksource/timer-digicolor.c | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-digicolor.c b/drivers/clocksource/timer-digicolor.c new file mode 100644 index 000000000..7f8388cfa --- /dev/null +++ b/drivers/clocksource/timer-digicolor.c @@ -0,0 +1,199 @@ +/* + * Conexant Digicolor timer driver + * + * Author: Baruch Siach <baruch@tkos.co.il> + * + * Copyright (C) 2014 Paradox Innovation Ltd. + * + * Based on: + * Allwinner SoCs hstimer driver + * + * Copyright (C) 2013 Maxime Ripard + * + * Maxime Ripard <maxime.ripard@free-electrons.com> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +/* + * Conexant Digicolor SoCs have 8 configurable timers, named from "Timer A" to + * "Timer H". Timer A is the only one with watchdog support, so it is dedicated + * to the watchdog driver. This driver uses Timer B for sched_clock(), and + * Timer C for clockevents. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/clk.h> +#include <linux/clockchips.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/irqreturn.h> +#include <linux/sched_clock.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> + +enum { + TIMER_A, + TIMER_B, + TIMER_C, + TIMER_D, + TIMER_E, + TIMER_F, + TIMER_G, + TIMER_H, +}; + +#define CONTROL(t) ((t)*8) +#define COUNT(t) ((t)*8 + 4) + +#define CONTROL_DISABLE 0 +#define CONTROL_ENABLE BIT(0) +#define CONTROL_MODE(m) ((m) << 4) +#define CONTROL_MODE_ONESHOT CONTROL_MODE(1) +#define CONTROL_MODE_PERIODIC CONTROL_MODE(2) + +struct digicolor_timer { + struct clock_event_device ce; + void __iomem *base; + u32 ticks_per_jiffy; + int timer_id; /* one of TIMER_* */ +}; + +struct digicolor_timer *dc_timer(struct clock_event_device *ce) +{ + return container_of(ce, struct digicolor_timer, ce); +} + +static inline void dc_timer_disable(struct clock_event_device *ce) +{ + struct digicolor_timer *dt = dc_timer(ce); + writeb(CONTROL_DISABLE, dt->base + CONTROL(dt->timer_id)); +} + +static inline void dc_timer_enable(struct clock_event_device *ce, u32 mode) +{ + struct digicolor_timer *dt = dc_timer(ce); + writeb(CONTROL_ENABLE | mode, dt->base + CONTROL(dt->timer_id)); +} + +static inline void dc_timer_set_count(struct clock_event_device *ce, + unsigned long count) +{ + struct digicolor_timer *dt = dc_timer(ce); + writel(count, dt->base + COUNT(dt->timer_id)); +} + +static void digicolor_clkevt_mode(enum clock_event_mode mode, + struct clock_event_device *ce) +{ + struct digicolor_timer *dt = dc_timer(ce); + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + dc_timer_disable(ce); + dc_timer_set_count(ce, dt->ticks_per_jiffy); + dc_timer_enable(ce, CONTROL_MODE_PERIODIC); + break; + case CLOCK_EVT_MODE_ONESHOT: + dc_timer_disable(ce); + dc_timer_enable(ce, CONTROL_MODE_ONESHOT); + break; + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + default: + dc_timer_disable(ce); + break; + } +} + +static int digicolor_clkevt_next_event(unsigned long evt, + struct clock_event_device *ce) +{ + dc_timer_disable(ce); + dc_timer_set_count(ce, evt); + dc_timer_enable(ce, CONTROL_MODE_ONESHOT); + + return 0; +} + +static struct digicolor_timer dc_timer_dev = { + .ce = { + .name = "digicolor_tick", + .rating = 340, + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .set_mode = digicolor_clkevt_mode, + .set_next_event = digicolor_clkevt_next_event, + }, + .timer_id = TIMER_C, +}; + +static irqreturn_t digicolor_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static u64 digicolor_timer_sched_read(void) +{ + return ~readl(dc_timer_dev.base + COUNT(TIMER_B)); +} + +static void __init digicolor_timer_init(struct device_node *node) +{ + unsigned long rate; + struct clk *clk; + int ret, irq; + + /* + * timer registers are shared with the watchdog timer; + * don't map exclusively + */ + dc_timer_dev.base = of_iomap(node, 0); + if (!dc_timer_dev.base) { + pr_err("Can't map registers"); + return; + } + + irq = irq_of_parse_and_map(node, dc_timer_dev.timer_id); + if (irq <= 0) { + pr_err("Can't parse IRQ"); + return; + } + + clk = of_clk_get(node, 0); + if (IS_ERR(clk)) { + pr_err("Can't get timer clock"); + return; + } + clk_prepare_enable(clk); + rate = clk_get_rate(clk); + dc_timer_dev.ticks_per_jiffy = DIV_ROUND_UP(rate, HZ); + + writeb(CONTROL_DISABLE, dc_timer_dev.base + CONTROL(TIMER_B)); + writel(UINT_MAX, dc_timer_dev.base + COUNT(TIMER_B)); + writeb(CONTROL_ENABLE, dc_timer_dev.base + CONTROL(TIMER_B)); + + sched_clock_register(digicolor_timer_sched_read, 32, rate); + clocksource_mmio_init(dc_timer_dev.base + COUNT(TIMER_B), node->name, + rate, 340, 32, clocksource_mmio_readl_down); + + ret = request_irq(irq, digicolor_timer_interrupt, + IRQF_TIMER | IRQF_IRQPOLL, "digicolor_timerC", + &dc_timer_dev.ce); + if (ret) + pr_warn("request of timer irq %d failed (%d)\n", irq, ret); + + dc_timer_dev.ce.cpumask = cpu_possible_mask; + dc_timer_dev.ce.irq = irq; + + clockevents_config_and_register(&dc_timer_dev.ce, rate, 0, 0xffffffff); +} +CLOCKSOURCE_OF_DECLARE(conexant_digicolor, "cnxt,cx92755-timer", + digicolor_timer_init); |