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Diffstat (limited to 'arch/arm/mach-omap2/timer.c')
| -rw-r--r-- | arch/arm/mach-omap2/timer.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c new file mode 100644 index 000000000..5677c4a08 --- /dev/null +++ b/arch/arm/mach-omap2/timer.c @@ -0,0 +1,167 @@ +/* + * linux/arch/arm/mach-omap2/timer.c + * + * OMAP2 GP 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> + * + * 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. + */ +#include <linux/clk.h> +#include <linux/clocksource.h> + +#include "soc.h" +#include "common.h" +#include "control.h" +#include "omap-secure.h" + +#define REALTIME_COUNTER_BASE 0x48243200 +#define INCREMENTER_NUMERATOR_OFFSET 0x10 +#define INCREMENTER_DENUMERATOR_RELOAD_OFFSET 0x14 +#define NUMERATOR_DENUMERATOR_MASK 0xfffff000 + +static unsigned long arch_timer_freq; + +void set_cntfreq(void) +{ + omap_smc1(OMAP5_DRA7_MON_SET_CNTFRQ_INDEX, arch_timer_freq); +} + +/* + * The realtime counter also called master counter, is a free-running + * counter, which is related to real time. It produces the count used + * by the CPU local timer peripherals in the MPU cluster. The timer counts + * at a rate of 6.144 MHz. Because the device operates on different clocks + * in different power modes, the master counter shifts operation between + * clocks, adjusting the increment per clock in hardware accordingly to + * maintain a constant count rate. + */ +static void __init realtime_counter_init(void) +{ + void __iomem *base; + static struct clk *sys_clk; + unsigned long rate; + unsigned int reg; + unsigned long long num, den; + + base = ioremap(REALTIME_COUNTER_BASE, SZ_32); + if (!base) { + pr_err("%s: ioremap failed\n", __func__); + return; + } + sys_clk = clk_get(NULL, "sys_clkin"); + if (IS_ERR(sys_clk)) { + pr_err("%s: failed to get system clock handle\n", __func__); + iounmap(base); + return; + } + + rate = clk_get_rate(sys_clk); + clk_put(sys_clk); + + if (soc_is_dra7xx()) { + /* + * Errata i856 says the 32.768KHz crystal does not start at + * power on, so the CPU falls back to an emulated 32KHz clock + * based on sysclk / 610 instead. This causes the master counter + * frequency to not be 6.144MHz but at sysclk / 610 * 375 / 2 + * (OR sysclk * 75 / 244) + * + * This affects at least the DRA7/AM572x 1.0, 1.1 revisions. + * Of course any board built without a populated 32.768KHz + * crystal would also need this fix even if the CPU is fixed + * later. + * + * Either case can be detected by using the two speedselect bits + * If they are not 0, then the 32.768KHz clock driving the + * coarse counter that corrects the fine counter every time it + * ticks is actually rate/610 rather than 32.768KHz and we + * should compensate to avoid the 570ppm (at 20MHz, much worse + * at other rates) too fast system time. + */ + reg = omap_ctrl_readl(DRA7_CTRL_CORE_BOOTSTRAP); + if (reg & DRA7_SPEEDSELECT_MASK) { + num = 75; + den = 244; + goto sysclk1_based; + } + } + + /* Numerator/denumerator values refer TRM Realtime Counter section */ + switch (rate) { + case 12000000: + num = 64; + den = 125; + break; + case 13000000: + num = 768; + den = 1625; + break; + case 19200000: + num = 8; + den = 25; + break; + case 20000000: + num = 192; + den = 625; + break; + case 26000000: + num = 384; + den = 1625; + break; + case 27000000: + num = 256; + den = 1125; + break; + case 38400000: + default: + /* Program it for 38.4 MHz */ + num = 4; + den = 25; + break; + } + +sysclk1_based: + /* Program numerator and denumerator registers */ + reg = readl_relaxed(base + INCREMENTER_NUMERATOR_OFFSET) & + NUMERATOR_DENUMERATOR_MASK; + reg |= num; + writel_relaxed(reg, base + INCREMENTER_NUMERATOR_OFFSET); + + reg = readl_relaxed(base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET) & + NUMERATOR_DENUMERATOR_MASK; + reg |= den; + writel_relaxed(reg, base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET); + + arch_timer_freq = DIV_ROUND_UP_ULL(rate * num, den); + set_cntfreq(); + + iounmap(base); +} + +void __init omap5_realtime_timer_init(void) +{ + omap_clk_init(); + realtime_counter_init(); + + timer_probe(); +} |