diff options
Diffstat (limited to 'kernel/drivers/clocksource/timer-ti-32k.c')
| -rw-r--r-- | kernel/drivers/clocksource/timer-ti-32k.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/kernel/drivers/clocksource/timer-ti-32k.c b/kernel/drivers/clocksource/timer-ti-32k.c new file mode 100644 index 000000000..8518d9dfb --- /dev/null +++ b/kernel/drivers/clocksource/timer-ti-32k.c @@ -0,0 +1,126 @@ +/** + * timer-ti-32k.c - OMAP2 32k Timer Support + * + * Copyright (C) 2009 Nokia Corporation + * + * Update to use new clocksource/clockevent layers + * Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com> + * Copyright (C) 2007 MontaVista Software, Inc. + * + * Original driver: + * Copyright (C) 2005 Nokia Corporation + * Author: Paul Mundt <paul.mundt@nokia.com> + * Juha Yrjölä <juha.yrjola@nokia.com> + * OMAP Dual-mode timer framework support by Timo Teras + * + * Some parts based off of TI's 24xx code: + * + * Copyright (C) 2004-2009 Texas Instruments, Inc. + * + * Roughly modelled after the OMAP1 MPU timer code. + * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com> + * + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 of + * the License as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/init.h> +#include <linux/time.h> +#include <linux/sched_clock.h> +#include <linux/clocksource.h> +#include <linux/of.h> +#include <linux/of_address.h> + +/* + * 32KHz clocksource ... always available, on pretty most chips except + * OMAP 730 and 1510. Other timers could be used as clocksources, with + * higher resolution in free-running counter modes (e.g. 12 MHz xtal), + * but systems won't necessarily want to spend resources that way. + */ + +#define OMAP2_32KSYNCNT_REV_OFF 0x0 +#define OMAP2_32KSYNCNT_REV_SCHEME (0x3 << 30) +#define OMAP2_32KSYNCNT_CR_OFF_LOW 0x10 +#define OMAP2_32KSYNCNT_CR_OFF_HIGH 0x30 + +struct ti_32k { + void __iomem *base; + void __iomem *counter; + struct clocksource cs; +}; + +static inline struct ti_32k *to_ti_32k(struct clocksource *cs) +{ + return container_of(cs, struct ti_32k, cs); +} + +static cycle_t ti_32k_read_cycles(struct clocksource *cs) +{ + struct ti_32k *ti = to_ti_32k(cs); + + return (cycle_t)readl_relaxed(ti->counter); +} + +static struct ti_32k ti_32k_timer = { + .cs = { + .name = "32k_counter", + .rating = 250, + .read = ti_32k_read_cycles, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS | + CLOCK_SOURCE_SUSPEND_NONSTOP, + }, +}; + +static u64 notrace omap_32k_read_sched_clock(void) +{ + return ti_32k_read_cycles(&ti_32k_timer.cs); +} + +static void __init ti_32k_timer_init(struct device_node *np) +{ + int ret; + + ti_32k_timer.base = of_iomap(np, 0); + if (!ti_32k_timer.base) { + pr_err("Can't ioremap 32k timer base\n"); + return; + } + + ti_32k_timer.counter = ti_32k_timer.base; + + /* + * 32k sync Counter IP register offsets vary between the highlander + * version and the legacy ones. + * + * The 'SCHEME' bits(30-31) of the revision register is used to identify + * the version. + */ + if (readl_relaxed(ti_32k_timer.base + OMAP2_32KSYNCNT_REV_OFF) & + OMAP2_32KSYNCNT_REV_SCHEME) + ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_HIGH; + else + ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_LOW; + + ret = clocksource_register_hz(&ti_32k_timer.cs, 32768); + if (ret) { + pr_err("32k_counter: can't register clocksource\n"); + return; + } + + sched_clock_register(omap_32k_read_sched_clock, 32, 32768); + pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n"); +} +CLOCKSOURCE_OF_DECLARE(ti_32k_timer, "ti,omap-counter32k", + ti_32k_timer_init); |