diff options
Diffstat (limited to 'drivers/clocksource/h8300_timer16.c')
| -rw-r--r-- | drivers/clocksource/h8300_timer16.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/clocksource/h8300_timer16.c b/drivers/clocksource/h8300_timer16.c new file mode 100644 index 000000000..86ca91451 --- /dev/null +++ b/drivers/clocksource/h8300_timer16.c @@ -0,0 +1,192 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * H8/300 16bit Timer driver + * + * Copyright 2015 Yoshinori Sato <ysato@users.sourcefoge.jp> + */ + +#include <linux/interrupt.h> +#include <linux/init.h> +#include <linux/clocksource.h> +#include <linux/clk.h> +#include <linux/io.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> + +#define TSTR 0 +#define TISRC 6 + +#define TCR 0 +#define TCNT 2 + +#define bset(b, a) iowrite8(ioread8(a) | (1 << (b)), (a)) +#define bclr(b, a) iowrite8(ioread8(a) & ~(1 << (b)), (a)) + +struct timer16_priv { + struct clocksource cs; + unsigned long total_cycles; + void __iomem *mapbase; + void __iomem *mapcommon; + unsigned short cs_enabled; + unsigned char enb; + unsigned char ovf; + unsigned char ovie; +}; + +static unsigned long timer16_get_counter(struct timer16_priv *p) +{ + unsigned short v1, v2, v3; + unsigned char o1, o2; + + o1 = ioread8(p->mapcommon + TISRC) & p->ovf; + + /* Make sure the timer value is stable. Stolen from acpi_pm.c */ + do { + o2 = o1; + v1 = ioread16be(p->mapbase + TCNT); + v2 = ioread16be(p->mapbase + TCNT); + v3 = ioread16be(p->mapbase + TCNT); + o1 = ioread8(p->mapcommon + TISRC) & p->ovf; + } while (unlikely((o1 != o2) || (v1 > v2 && v1 < v3) + || (v2 > v3 && v2 < v1) || (v3 > v1 && v3 < v2))); + + if (likely(!o1)) + return v2; + else + return v2 + 0x10000; +} + + +static irqreturn_t timer16_interrupt(int irq, void *dev_id) +{ + struct timer16_priv *p = (struct timer16_priv *)dev_id; + + bclr(p->ovf, p->mapcommon + TISRC); + p->total_cycles += 0x10000; + + return IRQ_HANDLED; +} + +static inline struct timer16_priv *cs_to_priv(struct clocksource *cs) +{ + return container_of(cs, struct timer16_priv, cs); +} + +static u64 timer16_clocksource_read(struct clocksource *cs) +{ + struct timer16_priv *p = cs_to_priv(cs); + unsigned long raw, value; + + value = p->total_cycles; + raw = timer16_get_counter(p); + + return value + raw; +} + +static int timer16_enable(struct clocksource *cs) +{ + struct timer16_priv *p = cs_to_priv(cs); + + WARN_ON(p->cs_enabled); + + p->total_cycles = 0; + iowrite16be(0x0000, p->mapbase + TCNT); + iowrite8(0x83, p->mapbase + TCR); + bset(p->ovie, p->mapcommon + TISRC); + bset(p->enb, p->mapcommon + TSTR); + + p->cs_enabled = true; + return 0; +} + +static void timer16_disable(struct clocksource *cs) +{ + struct timer16_priv *p = cs_to_priv(cs); + + WARN_ON(!p->cs_enabled); + + bclr(p->ovie, p->mapcommon + TISRC); + bclr(p->enb, p->mapcommon + TSTR); + + p->cs_enabled = false; +} + +static struct timer16_priv timer16_priv = { + .cs = { + .name = "h8300_16timer", + .rating = 200, + .read = timer16_clocksource_read, + .enable = timer16_enable, + .disable = timer16_disable, + .mask = CLOCKSOURCE_MASK(sizeof(unsigned long) * 8), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + }, +}; + +#define REG_CH 0 +#define REG_COMM 1 + +static int __init h8300_16timer_init(struct device_node *node) +{ + void __iomem *base[2]; + int ret, irq; + unsigned int ch; + struct clk *clk; + + clk = of_clk_get(node, 0); + if (IS_ERR(clk)) { + pr_err("failed to get clock for clocksource\n"); + return PTR_ERR(clk); + } + + ret = -ENXIO; + base[REG_CH] = of_iomap(node, 0); + if (!base[REG_CH]) { + pr_err("failed to map registers for clocksource\n"); + goto free_clk; + } + + base[REG_COMM] = of_iomap(node, 1); + if (!base[REG_COMM]) { + pr_err("failed to map registers for clocksource\n"); + goto unmap_ch; + } + + ret = -EINVAL; + irq = irq_of_parse_and_map(node, 0); + if (!irq) { + pr_err("failed to get irq for clockevent\n"); + goto unmap_comm; + } + + of_property_read_u32(node, "renesas,channel", &ch); + + timer16_priv.mapbase = base[REG_CH]; + timer16_priv.mapcommon = base[REG_COMM]; + timer16_priv.enb = ch; + timer16_priv.ovf = ch; + timer16_priv.ovie = 4 + ch; + + ret = request_irq(irq, timer16_interrupt, + IRQF_TIMER, timer16_priv.cs.name, &timer16_priv); + if (ret < 0) { + pr_err("failed to request irq %d of clocksource\n", irq); + goto unmap_comm; + } + + clocksource_register_hz(&timer16_priv.cs, + clk_get_rate(clk) / 8); + return 0; + +unmap_comm: + iounmap(base[REG_COMM]); +unmap_ch: + iounmap(base[REG_CH]); +free_clk: + clk_put(clk); + return ret; +} + +TIMER_OF_DECLARE(h8300_16bit, "renesas,16bit-timer", + h8300_16timer_init); |