diff options
Diffstat (limited to 'arch/avr32/mach-at32ap/time-tc.c')
| -rw-r--r-- | arch/avr32/mach-at32ap/time-tc.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/arch/avr32/mach-at32ap/time-tc.c b/arch/avr32/mach-at32ap/time-tc.c new file mode 100644 index 00000000000..e3070bdd4bb --- /dev/null +++ b/arch/avr32/mach-at32ap/time-tc.c @@ -0,0 +1,218 @@ +/* + * Copyright (C) 2004-2007 Atmel Corporation + * + * Based on MIPS implementation arch/mips/kernel/time.c + * Copyright 2001 MontaVista Software Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/clk.h> +#include <linux/clocksource.h> +#include <linux/time.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/kernel_stat.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/profile.h> +#include <linux/sysdev.h> +#include <linux/err.h> + +#include <asm/div64.h> +#include <asm/sysreg.h> +#include <asm/io.h> +#include <asm/sections.h> + +#include <asm/arch/time.h> + +/* how many counter cycles in a jiffy? */ +static u32 cycles_per_jiffy; + +/* the count value for the next timer interrupt */ +static u32 expirelo; + +/* the I/O registers of the TC module */ +static void __iomem *ioregs; + +cycle_t read_cycle_count(void) +{ + return (cycle_t)timer_read(ioregs, 0, CV); +} + +struct clocksource clocksource_avr32 = { + .name = "avr32", + .rating = 342, + .read = read_cycle_count, + .mask = CLOCKSOURCE_MASK(16), + .shift = 16, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static void avr32_timer_ack(void) +{ + u16 count = expirelo; + + /* Ack this timer interrupt and set the next one, use a u16 + * variable so it will wrap around correctly */ + count += cycles_per_jiffy; + expirelo = count; + timer_write(ioregs, 0, RC, expirelo); + + /* Check to see if we have missed any timer interrupts */ + count = timer_read(ioregs, 0, CV); + if ((count - expirelo) < 0x7fff) { + expirelo = count + cycles_per_jiffy; + timer_write(ioregs, 0, RC, expirelo); + } +} + +u32 avr32_hpt_read(void) +{ + return timer_read(ioregs, 0, CV); +} + +static int avr32_timer_calc_div_and_set_jiffies(struct clk *pclk) +{ + unsigned int cycles_max = (clocksource_avr32.mask + 1) / 2; + unsigned int divs[] = { 4, 8, 16, 32 }; + int divs_size = sizeof(divs) / sizeof(*divs); + int i = 0; + unsigned long count_hz; + unsigned long shift; + unsigned long mult; + int clock_div = -1; + u64 tmp; + + shift = clocksource_avr32.shift; + + do { + count_hz = clk_get_rate(pclk) / divs[i]; + mult = clocksource_hz2mult(count_hz, shift); + clocksource_avr32.mult = mult; + + tmp = TICK_NSEC; + tmp <<= shift; + tmp += mult / 2; + do_div(tmp, mult); + + cycles_per_jiffy = tmp; + } while (cycles_per_jiffy > cycles_max && ++i < divs_size); + + clock_div = i + 1; + + if (clock_div > divs_size) { + pr_debug("timer: could not calculate clock divider\n"); + return -EFAULT; + } + + /* Set the clock divider */ + timer_write(ioregs, 0, CMR, TIMER_BF(CMR_TCCLKS, clock_div)); + + return 0; +} + +int avr32_hpt_init(unsigned int count) +{ + struct resource *regs; + struct clk *pclk; + int irq = -1; + int ret = 0; + + ret = -ENXIO; + + irq = platform_get_irq(&at32_systc0_device, 0); + if (irq < 0) { + pr_debug("timer: could not get irq\n"); + goto out_error; + } + + pclk = clk_get(&at32_systc0_device.dev, "pclk"); + if (IS_ERR(pclk)) { + pr_debug("timer: could not get clk: %ld\n", PTR_ERR(pclk)); + goto out_error; + } + clk_enable(pclk); + + regs = platform_get_resource(&at32_systc0_device, IORESOURCE_MEM, 0); + if (!regs) { + pr_debug("timer: could not get resource\n"); + goto out_error_clk; + } + + ioregs = ioremap(regs->start, regs->end - regs->start + 1); + if (!ioregs) { + pr_debug("timer: could not get ioregs\n"); + goto out_error_clk; + } + + ret = avr32_timer_calc_div_and_set_jiffies(pclk); + if (ret) + goto out_error_io; + + ret = setup_irq(irq, &timer_irqaction); + if (ret) { + pr_debug("timer: could not request irq %d: %d\n", + irq, ret); + goto out_error_io; + } + + expirelo = (timer_read(ioregs, 0, CV) / cycles_per_jiffy + 1) + * cycles_per_jiffy; + + /* Enable clock and interrupts on RC compare */ + timer_write(ioregs, 0, CCR, TIMER_BIT(CCR_CLKEN)); + timer_write(ioregs, 0, IER, TIMER_BIT(IER_CPCS)); + /* Set cycles to first interrupt */ + timer_write(ioregs, 0, RC, expirelo); + + printk(KERN_INFO "timer: AT32AP system timer/counter at 0x%p irq %d\n", + ioregs, irq); + + return 0; + +out_error_io: + iounmap(ioregs); +out_error_clk: + clk_put(pclk); +out_error: + return ret; +} + +int avr32_hpt_start(void) +{ + timer_write(ioregs, 0, CCR, TIMER_BIT(CCR_SWTRG)); + return 0; +} + +irqreturn_t timer_interrupt(int irq, void *dev_id) +{ + unsigned int sr = timer_read(ioregs, 0, SR); + + if (sr & TIMER_BIT(SR_CPCS)) { + /* ack timer interrupt and try to set next interrupt */ + avr32_timer_ack(); + + /* + * Call the generic timer interrupt handler + */ + write_seqlock(&xtime_lock); + do_timer(1); + write_sequnlock(&xtime_lock); + + /* + * In UP mode, we call local_timer_interrupt() to do profiling + * and process accounting. + * + * SMP is not supported yet. + */ + local_timer_interrupt(irq, dev_id); + + return IRQ_HANDLED; + } + + return IRQ_NONE; +} |