diff options
Diffstat (limited to 'arch/arm/mach-zynq')
-rw-r--r-- | arch/arm/mach-zynq/common.c | 1 | ||||
-rw-r--r-- | arch/arm/mach-zynq/timer.c | 261 |
2 files changed, 189 insertions, 73 deletions
diff --git a/arch/arm/mach-zynq/common.c b/arch/arm/mach-zynq/common.c index 5c898321818..76493b050be 100644 --- a/arch/arm/mach-zynq/common.c +++ b/arch/arm/mach-zynq/common.c @@ -20,6 +20,7 @@ #include <linux/platform_device.h> #include <linux/clk.h> #include <linux/clk/zynq.h> +#include <linux/clocksource.h> #include <linux/of_address.h> #include <linux/of_irq.h> #include <linux/of_platform.h> diff --git a/arch/arm/mach-zynq/timer.c b/arch/arm/mach-zynq/timer.c index f9fbc9c1e7a..82357d94a0e 100644 --- a/arch/arm/mach-zynq/timer.c +++ b/arch/arm/mach-zynq/timer.c @@ -1,7 +1,7 @@ /* * This file contains driver for the Xilinx PS Timer Counter IP. * - * Copyright (C) 2011 Xilinx + * Copyright (C) 2011-2013 Xilinx * * based on arch/mips/kernel/time.c timer driver * @@ -15,6 +15,7 @@ * GNU General Public License for more details. */ +#include <linux/clk.h> #include <linux/interrupt.h> #include <linux/clockchips.h> #include <linux/of_address.h> @@ -24,6 +25,21 @@ #include "common.h" /* + * This driver configures the 2 16-bit count-up timers as follows: + * + * T1: Timer 1, clocksource for generic timekeeping + * T2: Timer 2, clockevent source for hrtimers + * T3: Timer 3, <unused> + * + * The input frequency to the timer module for emulation is 2.5MHz which is + * common to all the timer channels (T1, T2, and T3). With a pre-scaler of 32, + * the timers are clocked at 78.125KHz (12.8 us resolution). + + * The input frequency to the timer module in silicon is configurable and + * obtained from device tree. The pre-scaler of 32 is used. + */ + +/* * Timer Register Offset Definitions of Timer 1, Increment base address by 4 * and use same offsets for Timer 2 */ @@ -44,17 +60,24 @@ #define PRESCALE 2048 /* The exponent must match this */ #define CLK_CNTRL_PRESCALE ((PRESCALE_EXPONENT - 1) << 1) #define CLK_CNTRL_PRESCALE_EN 1 -#define CNT_CNTRL_RESET (1<<4) +#define CNT_CNTRL_RESET (1 << 4) /** * struct xttcps_timer - This definition defines local timer structure * * @base_addr: Base address of timer - **/ + * @clk: Associated clock source + * @clk_rate_change_nb Notifier block for clock rate changes + */ struct xttcps_timer { - void __iomem *base_addr; + void __iomem *base_addr; + struct clk *clk; + struct notifier_block clk_rate_change_nb; }; +#define to_xttcps_timer(x) \ + container_of(x, struct xttcps_timer, clk_rate_change_nb) + struct xttcps_timer_clocksource { struct xttcps_timer xttc; struct clocksource cs; @@ -66,7 +89,6 @@ struct xttcps_timer_clocksource { struct xttcps_timer_clockevent { struct xttcps_timer xttc; struct clock_event_device ce; - struct clk *clk; }; #define to_xttcps_timer_clkevent(x) \ @@ -167,8 +189,8 @@ static void xttcps_set_mode(enum clock_event_mode mode, switch (mode) { case CLOCK_EVT_MODE_PERIODIC: xttcps_set_interval(timer, - DIV_ROUND_CLOSEST(clk_get_rate(xttce->clk), - PRESCALE * HZ)); + DIV_ROUND_CLOSEST(clk_get_rate(xttce->xttc.clk), + PRESCALE * HZ)); break; case CLOCK_EVT_MODE_ONESHOT: case CLOCK_EVT_MODE_UNUSED: @@ -189,79 +211,148 @@ static void xttcps_set_mode(enum clock_event_mode mode, } } -static void __init zynq_ttc_setup_clocksource(struct device_node *np, - void __iomem *base) +static int xttcps_rate_change_clocksource_cb(struct notifier_block *nb, + unsigned long event, void *data) +{ + struct clk_notifier_data *ndata = data; + struct xttcps_timer *xttcps = to_xttcps_timer(nb); + struct xttcps_timer_clocksource *xttccs = container_of(xttcps, + struct xttcps_timer_clocksource, xttc); + + switch (event) { + case POST_RATE_CHANGE: + /* + * Do whatever is necessary to maintain a proper time base + * + * I cannot find a way to adjust the currently used clocksource + * to the new frequency. __clocksource_updatefreq_hz() sounds + * good, but does not work. Not sure what's that missing. + * + * This approach works, but triggers two clocksource switches. + * The first after unregister to clocksource jiffies. And + * another one after the register to the newly registered timer. + * + * Alternatively we could 'waste' another HW timer to ping pong + * between clock sources. That would also use one register and + * one unregister call, but only trigger one clocksource switch + * for the cost of another HW timer used by the OS. + */ + clocksource_unregister(&xttccs->cs); + clocksource_register_hz(&xttccs->cs, + ndata->new_rate / PRESCALE); + /* fall through */ + case PRE_RATE_CHANGE: + case ABORT_RATE_CHANGE: + default: + return NOTIFY_DONE; + } +} + +static void __init xttc_setup_clocksource(struct clk *clk, void __iomem *base) { struct xttcps_timer_clocksource *ttccs; - struct clk *clk; int err; - u32 reg; ttccs = kzalloc(sizeof(*ttccs), GFP_KERNEL); if (WARN_ON(!ttccs)) return; - err = of_property_read_u32(np, "reg", ®); - if (WARN_ON(err)) - return; + ttccs->xttc.clk = clk; - clk = of_clk_get_by_name(np, "cpu_1x"); - if (WARN_ON(IS_ERR(clk))) - return; - - err = clk_prepare_enable(clk); + err = clk_prepare_enable(ttccs->xttc.clk); if (WARN_ON(err)) return; - ttccs->xttc.base_addr = base + reg * 4; + ttccs->xttc.clk_rate_change_nb.notifier_call = + xttcps_rate_change_clocksource_cb; + ttccs->xttc.clk_rate_change_nb.next = NULL; + if (clk_notifier_register(ttccs->xttc.clk, + &ttccs->xttc.clk_rate_change_nb)) + pr_warn("Unable to register clock notifier.\n"); - ttccs->cs.name = np->name; + ttccs->xttc.base_addr = base; + ttccs->cs.name = "xttcps_clocksource"; ttccs->cs.rating = 200; ttccs->cs.read = __xttc_clocksource_read; ttccs->cs.mask = CLOCKSOURCE_MASK(16); ttccs->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS; + /* + * Setup the clock source counter to be an incrementing counter + * with no interrupt and it rolls over at 0xFFFF. Pre-scale + * it by 32 also. Let it start running now. + */ __raw_writel(0x0, ttccs->xttc.base_addr + XTTCPS_IER_OFFSET); __raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN, ttccs->xttc.base_addr + XTTCPS_CLK_CNTRL_OFFSET); __raw_writel(CNT_CNTRL_RESET, ttccs->xttc.base_addr + XTTCPS_CNT_CNTRL_OFFSET); - err = clocksource_register_hz(&ttccs->cs, clk_get_rate(clk) / PRESCALE); + err = clocksource_register_hz(&ttccs->cs, + clk_get_rate(ttccs->xttc.clk) / PRESCALE); if (WARN_ON(err)) return; + } -static void __init zynq_ttc_setup_clockevent(struct device_node *np, - void __iomem *base) +static int xttcps_rate_change_clockevent_cb(struct notifier_block *nb, + unsigned long event, void *data) +{ + struct clk_notifier_data *ndata = data; + struct xttcps_timer *xttcps = to_xttcps_timer(nb); + struct xttcps_timer_clockevent *xttcce = container_of(xttcps, + struct xttcps_timer_clockevent, xttc); + + switch (event) { + case POST_RATE_CHANGE: + { + unsigned long flags; + + /* + * clockevents_update_freq should be called with IRQ disabled on + * the CPU the timer provides events for. The timer we use is + * common to both CPUs, not sure if we need to run on both + * cores. + */ + local_irq_save(flags); + clockevents_update_freq(&xttcce->ce, + ndata->new_rate / PRESCALE); + local_irq_restore(flags); + + /* fall through */ + } + case PRE_RATE_CHANGE: + case ABORT_RATE_CHANGE: + default: + return NOTIFY_DONE; + } +} + +static void __init xttc_setup_clockevent(struct clk *clk, + void __iomem *base, u32 irq) { struct xttcps_timer_clockevent *ttcce; - int err, irq; - u32 reg; + int err; ttcce = kzalloc(sizeof(*ttcce), GFP_KERNEL); if (WARN_ON(!ttcce)) return; - err = of_property_read_u32(np, "reg", ®); - if (WARN_ON(err)) - return; + ttcce->xttc.clk = clk; - ttcce->xttc.base_addr = base + reg * 4; - - ttcce->clk = of_clk_get_by_name(np, "cpu_1x"); - if (WARN_ON(IS_ERR(ttcce->clk))) - return; - - err = clk_prepare_enable(ttcce->clk); + err = clk_prepare_enable(ttcce->xttc.clk); if (WARN_ON(err)) return; - irq = irq_of_parse_and_map(np, 0); - if (WARN_ON(!irq)) - return; + ttcce->xttc.clk_rate_change_nb.notifier_call = + xttcps_rate_change_clockevent_cb; + ttcce->xttc.clk_rate_change_nb.next = NULL; + if (clk_notifier_register(ttcce->xttc.clk, + &ttcce->xttc.clk_rate_change_nb)) + pr_warn("Unable to register clock notifier.\n"); - ttcce->ce.name = np->name; + ttcce->xttc.base_addr = base; + ttcce->ce.name = "xttcps_clockevent"; ttcce->ce.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; ttcce->ce.set_next_event = xttcps_set_next_event; ttcce->ce.set_mode = xttcps_set_mode; @@ -269,56 +360,80 @@ static void __init zynq_ttc_setup_clockevent(struct device_node *np, ttcce->ce.irq = irq; ttcce->ce.cpumask = cpu_possible_mask; + /* + * Setup the clock event timer to be an interval timer which + * is prescaled by 32 using the interval interrupt. Leave it + * disabled for now. + */ __raw_writel(0x23, ttcce->xttc.base_addr + XTTCPS_CNT_CNTRL_OFFSET); __raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN, ttcce->xttc.base_addr + XTTCPS_CLK_CNTRL_OFFSET); __raw_writel(0x1, ttcce->xttc.base_addr + XTTCPS_IER_OFFSET); - err = request_irq(irq, xttcps_clock_event_interrupt, IRQF_TIMER, - np->name, ttcce); + err = request_irq(irq, xttcps_clock_event_interrupt, + IRQF_DISABLED | IRQF_TIMER, + ttcce->ce.name, ttcce); if (WARN_ON(err)) return; clockevents_config_and_register(&ttcce->ce, - clk_get_rate(ttcce->clk) / PRESCALE, - 1, 0xfffe); + clk_get_rate(ttcce->xttc.clk) / PRESCALE, 1, 0xfffe); } -static const __initconst struct of_device_id zynq_ttc_match[] = { - { .compatible = "xlnx,ttc-counter-clocksource", - .data = zynq_ttc_setup_clocksource, }, - { .compatible = "xlnx,ttc-counter-clockevent", - .data = zynq_ttc_setup_clockevent, }, - {} -}; - /** * xttcps_timer_init - Initialize the timer * * Initializes the timer hardware and register the clock source and clock event * timers with Linux kernal timer framework - **/ + */ +static void __init xttcps_timer_init_of(struct device_node *timer) +{ + unsigned int irq; + void __iomem *timer_baseaddr; + struct clk *clk; + + /* + * Get the 1st Triple Timer Counter (TTC) block from the device tree + * and use it. Note that the event timer uses the interrupt and it's the + * 2nd TTC hence the irq_of_parse_and_map(,1) + */ + timer_baseaddr = of_iomap(timer, 0); + if (!timer_baseaddr) { + pr_err("ERROR: invalid timer base address\n"); + BUG(); + } + + irq = irq_of_parse_and_map(timer, 1); + if (irq <= 0) { + pr_err("ERROR: invalid interrupt number\n"); + BUG(); + } + + clk = of_clk_get_by_name(timer, "cpu_1x"); + if (IS_ERR(clk)) { + pr_err("ERROR: timer input clock not found\n"); + BUG(); + } + + xttc_setup_clocksource(clk, timer_baseaddr); + xttc_setup_clockevent(clk, timer_baseaddr + 4, irq); + + pr_info("%s #0 at %p, irq=%d\n", timer->name, timer_baseaddr, irq); +} + void __init xttcps_timer_init(void) { - struct device_node *np; - - for_each_compatible_node(np, NULL, "xlnx,ttc") { - struct device_node *np_chld; - void __iomem *base; - - base = of_iomap(np, 0); - if (WARN_ON(!base)) - return; - - for_each_available_child_of_node(np, np_chld) { - int (*cb)(struct device_node *np, void __iomem *base); - const struct of_device_id *match; - - match = of_match_node(zynq_ttc_match, np_chld); - if (match) { - cb = match->data; - cb(np_chld, base); - } - } + const char * const timer_list[] = { + "cdns,ttc", + NULL + }; + struct device_node *timer; + + timer = of_find_compatible_node(NULL, NULL, timer_list[0]); + if (!timer) { + pr_err("ERROR: no compatible timer found\n"); + BUG(); } + + xttcps_timer_init_of(timer); } |