Messages in this thread Patch in this message |  | | From | Alexey Charkov <> | | Date | Wed, 21 May 2025 17:00:11 +0400 | | Subject | [PATCH v5 3/4] clocksource/drivers/timer-vt8500: Prepare for watchdog functionality |
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VIA/WonderMedia system timer can generate a watchdog reset when its clocksource counter matches the value in the match register 0 and watchdog function is enabled. For this to work, obvously the clock event device must use a different match register (1~3) and respective interrupt.
Check if at least two interrupts are provided by the device tree, then use match register 1 for system clock events and reserve match register 0 for the watchdog. Instantiate an auxiliary device for the watchdog
Signed-off-by: Alexey Charkov <alchark@gmail.com> --- MAINTAINERS | 1 + drivers/clocksource/Kconfig | 1 + drivers/clocksource/timer-vt8500.c | 111 ++++++++++++++++++++++++++++++++++--- include/linux/vt8500-timer.h | 18 ++++++ 4 files changed, 122 insertions(+), 9 deletions(-)
diff --git a/MAINTAINERS b/MAINTAINERS index 783e5ee6854b69cca87b6f0763844d28b4b2213f..5362095240627f613638197fda275db6edc16cf7 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3447,6 +3447,7 @@ F: drivers/tty/serial/vt8500_serial.c F: drivers/video/fbdev/vt8500lcdfb.* F: drivers/video/fbdev/wm8505fb* F: drivers/video/fbdev/wmt_ge_rops.* +F: include/linux/vt8500-timer.h ARM/ZYNQ ARCHITECTURE M: Michal Simek <michal.simek@amd.com> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 487c8525996724fbf9c6e9726dabb478d86513b9..92f071aade10b7c0f0bba4b47dc6228a5e50360f 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -178,6 +178,7 @@ config TEGRA186_TIMER config VT8500_TIMER bool "VT8500 timer driver" if COMPILE_TEST depends on HAS_IOMEM + select AUXILIARY_BUS help Enables support for the VT8500 driver. diff --git a/drivers/clocksource/timer-vt8500.c b/drivers/clocksource/timer-vt8500.c index 9f28f30dcaf83ab4e9c89952175b0d4c75bd6b40..cdea5245f8e41d65b8b9bebad3fe3a55f43a18fa 100644 --- a/drivers/clocksource/timer-vt8500.c +++ b/drivers/clocksource/timer-vt8500.c @@ -11,6 +11,7 @@ * Alexey Charkov. Minor changes have been made for Device Tree Support. */ +#include <linux/auxiliary_bus.h> #include <linux/io.h> #include <linux/irq.h> #include <linux/interrupt.h> @@ -22,9 +23,6 @@ #include <linux/of_address.h> #include <linux/of_irq.h> -#define VT8500_TIMER_OFFSET 0x0100 -#define VT8500_TIMER_HZ 3000000 - #define TIMER_MATCH_REG(x) (4 * (x)) #define TIMER_COUNT_REG 0x0010 /* clocksource counter */ @@ -53,8 +51,14 @@ #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) #define MIN_OSCR_DELTA 16 +#include <linux/of_platform.h> +#include <linux/platform_device.h> +#include <linux/vt8500-timer.h> static void __iomem *regbase; +static unsigned int sys_timer_ch; /* which match register to use + * for the system timer + */ static u64 vt8500_timer_read(struct clocksource *cs) { @@ -75,21 +79,26 @@ static struct clocksource clocksource = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; +static u64 vt8500_timer_next(u64 cycles) +{ + return clocksource.read(&clocksource) + cycles; +} + static int vt8500_timer_set_next_event(unsigned long cycles, struct clock_event_device *evt) { int loops = msecs_to_loops(10); - u64 alarm = clocksource.read(&clocksource) + cycles; + u64 alarm = vt8500_timer_next(cycles); - while (readl(regbase + TIMER_ACC_STS_REG) & TIMER_ACC_WR_MATCH(0) + while (readl(regbase + TIMER_ACC_STS_REG) & TIMER_ACC_WR_MATCH(sys_timer_ch) && --loops) cpu_relax(); - writel((unsigned long)alarm, regbase + TIMER_MATCH_REG(0)); + writel((unsigned long)alarm, regbase + TIMER_MATCH_REG(sys_timer_ch)); if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA) return -ETIME; - writel(TIMER_INT_EN_MATCH(0), regbase + TIMER_INT_EN_REG); + writel(TIMER_INT_EN_MATCH(sys_timer_ch), regbase + TIMER_INT_EN_REG); return 0; } @@ -131,7 +140,9 @@ static int __init vt8500_timer_init(struct device_node *np) return -ENXIO; } - timer_irq = irq_of_parse_and_map(np, 0); + sys_timer_ch = of_irq_count(np) > 1 ? 1 : 0; + + timer_irq = irq_of_parse_and_map(np, sys_timer_ch); if (!timer_irq) { pr_err("%s: Missing irq description in Device Tree\n", __func__); @@ -140,7 +151,7 @@ static int __init vt8500_timer_init(struct device_node *np) writel(TIMER_CTRL_ENABLE, regbase + TIMER_CTRL_REG); writel(TIMER_STATUS_CLEARALL, regbase + TIMER_STATUS_REG); - writel(~0, regbase + TIMER_MATCH_REG(0)); + writel(~0, regbase + TIMER_MATCH_REG(sys_timer_ch)); ret = clocksource_register_hz(&clocksource, VT8500_TIMER_HZ); if (ret) { @@ -166,4 +177,86 @@ static int __init vt8500_timer_init(struct device_node *np) return 0; } +static void vt8500_timer_aux_uninit(void *data) +{ + auxiliary_device_uninit(data); +} + +static void vt8500_timer_aux_delete(void *data) +{ + auxiliary_device_delete(data); +} + +static void vt8500_timer_aux_release(struct device *dev) +{ + struct auxiliary_device *aux; + + aux = container_of(dev, struct auxiliary_device, dev); + kfree(aux); +} + +/* + * This probe gets called after the timer is already up and running. This will + * create the watchdog device as a child since the registers are shared. + */ +static int vt8500_timer_probe(struct platform_device *pdev) +{ + struct vt8500_wdt_info *wdt_info; + struct device *dev = &pdev->dev; + int ret; + + if (!sys_timer_ch) { + dev_info(dev, "Not enabling watchdog: only one irq was given"); + return 0; + } + + if (!regbase) + return dev_err_probe(dev, -ENOMEM, + "Timer not initialized, cannot create watchdog"); + + wdt_info = kzalloc(sizeof(*wdt_info), GFP_KERNEL); + if (!wdt_info) + return dev_err_probe(dev, -ENOMEM, + "Failed to allocate vt8500-wdt info"); + + wdt_info->timer_next = &vt8500_timer_next; + wdt_info->wdt_en = regbase + TIMER_WATCHDOG_EN_REG; + wdt_info->wdt_match = regbase + TIMER_MATCH_REG(0); + wdt_info->auxdev.name = "vt8500-wdt"; + wdt_info->auxdev.dev.parent = dev; + wdt_info->auxdev.dev.release = &vt8500_timer_aux_release; + + ret = auxiliary_device_init(&wdt_info->auxdev); + if (ret) { + kfree(wdt_info); + return ret; + } + ret = devm_add_action_or_reset(dev, vt8500_timer_aux_uninit, + &wdt_info->auxdev); + if (ret) + return ret; + + ret = auxiliary_device_add(&wdt_info->auxdev); + if (ret) + return ret; + return devm_add_action_or_reset(dev, vt8500_timer_aux_delete, + &wdt_info->auxdev); +} + +static const struct of_device_id vt8500_timer_of_match[] = { + { .compatible = "via,vt8500-timer", }, + {}, +}; + +static struct platform_driver vt8500_timer_driver = { + .probe = vt8500_timer_probe, + .driver = { + .name = "vt8500-timer", + .of_match_table = vt8500_timer_of_match, + .suppress_bind_attrs = true, + }, +}; + +builtin_platform_driver(vt8500_timer_driver); + TIMER_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init); diff --git a/include/linux/vt8500-timer.h b/include/linux/vt8500-timer.h new file mode 100644 index 0000000000000000000000000000000000000000..b8e9000495c509e9c8e8f4098d6bd33de27b3ec4 --- /dev/null +++ b/include/linux/vt8500-timer.h @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef LINUX_VT8500_TIMER_H_ +#define LINUX_VT8500_TIMER_H_ + +#include <linux/auxiliary_bus.h> +#include <linux/io.h> +#include <linux/types.h> + +#define VT8500_TIMER_HZ 3000000 + +struct vt8500_wdt_info { + struct auxiliary_device auxdev; + u64 (*timer_next)(u64 cycles); + void __iomem *wdt_en; + void __iomem *wdt_match; +}; + +#endif /* LINUX_VT8500_TIMER_H_ */ -- 2.49.0
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