diff options
| -rw-r--r-- | drivers/clocksource/Kconfig | 4 | ||||
| -rw-r--r-- | drivers/clocksource/arm_global_timer.c | 44 |
2 files changed, 41 insertions, 7 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 0fd662f67d29..ffcd23668763 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -395,8 +395,7 @@ config ARM_GLOBAL_TIMER config ARM_GT_INITIAL_PRESCALER_VAL int "ARM global timer initial prescaler value" - default 2 if ARCH_ZYNQ - default 1 + default 0 depends on ARM_GLOBAL_TIMER help When the ARM global timer initializes, its current rate is declared @@ -406,6 +405,7 @@ config ARM_GT_INITIAL_PRESCALER_VAL bounds about how much the parent clock is allowed to decrease or increase wrt the initial clock value. This affects CPU_FREQ max delta from the initial frequency. + Use 0 to use auto-detection in the driver. config ARM_TIMER_SP804 bool "Support for Dual Timer SP804 module" diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c index 2d86bbc2764a..5e3d6bb7e437 100644 --- a/drivers/clocksource/arm_global_timer.c +++ b/drivers/clocksource/arm_global_timer.c @@ -263,14 +263,13 @@ static void __init gt_delay_timer_init(void) register_current_timer_delay(>_delay_timer); } -static int __init gt_clocksource_init(void) +static int __init gt_clocksource_init(unsigned int psv) { writel(0, gt_base + GT_CONTROL); writel(0, gt_base + GT_COUNTER0); writel(0, gt_base + GT_COUNTER1); /* set prescaler and enable timer on all the cores */ - writel(FIELD_PREP(GT_CONTROL_PRESCALER_MASK, - CONFIG_ARM_GT_INITIAL_PRESCALER_VAL - 1) | + writel(FIELD_PREP(GT_CONTROL_PRESCALER_MASK, psv - 1) | GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL); #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK @@ -338,11 +337,45 @@ static int gt_clk_rate_change_cb(struct notifier_block *nb, return NOTIFY_DONE; } +struct gt_prescaler_config { + const char *compatible; + unsigned long prescaler; +}; + +static const struct gt_prescaler_config gt_prescaler_configs[] = { + /* + * On am43 the global timer clock is a child of the clock used for CPU + * OPPs, so the initial prescaler has to be compatible with all OPPs + * which are 300, 600, 720, 800 and 1000 with a fixed divider of 2, this + * gives us a GCD of 10. Initial frequency is 1000, so the prescaler is + * 50. + */ + { .compatible = "ti,am43", .prescaler = 50 }, + { .compatible = "xlnx,zynq-7000", .prescaler = 2 }, + { .compatible = NULL } +}; + +static unsigned long gt_get_initial_prescaler_value(struct device_node *np) +{ + const struct gt_prescaler_config *config; + + if (CONFIG_ARM_GT_INITIAL_PRESCALER_VAL != 0) + return CONFIG_ARM_GT_INITIAL_PRESCALER_VAL; + + for (config = gt_prescaler_configs; config->compatible; config++) { + if (of_machine_is_compatible(config->compatible)) + return config->prescaler; + } + + return 1; +} + static int __init global_timer_of_register(struct device_node *np) { struct clk *gt_clk; static unsigned long gt_clk_rate; int err; + unsigned long psv; /* * In A9 r2p0 the comparators for each processor with the global timer @@ -378,8 +411,9 @@ static int __init global_timer_of_register(struct device_node *np) goto out_unmap; } + psv = gt_get_initial_prescaler_value(np); gt_clk_rate = clk_get_rate(gt_clk); - gt_target_rate = gt_clk_rate / CONFIG_ARM_GT_INITIAL_PRESCALER_VAL; + gt_target_rate = gt_clk_rate / psv; gt_clk_rate_change_nb.notifier_call = gt_clk_rate_change_cb; err = clk_notifier_register(gt_clk, >_clk_rate_change_nb); @@ -404,7 +438,7 @@ static int __init global_timer_of_register(struct device_node *np) } /* Register and immediately configure the timer on the boot CPU */ - err = gt_clocksource_init(); + err = gt_clocksource_init(psv); if (err) goto out_irq; |