Re: [PATCH 12/16] clocksource: Add clock driver for RDA8810PL SoC
From: Marc Zyngier
Date: Mon Nov 19 2018 - 12:57:19 EST
On 19/11/2018 17:09, Manivannan Sadhasivam wrote:
> Add clock driver for RDA Micro RDA8810PL SoC supporting OSTIMER
> and HWTIMER.
>
> Signed-off-by: Andreas FÃrber <afaerber@xxxxxxx>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> ---
> arch/arm/mach-rda/Kconfig | 1 +
> drivers/clocksource/Kconfig | 7 ++
> drivers/clocksource/Makefile | 1 +
> drivers/clocksource/timer-rda.c | 187 ++++++++++++++++++++++++++++++++
> 4 files changed, 196 insertions(+)
> create mode 100644 drivers/clocksource/timer-rda.c
>
> diff --git a/arch/arm/mach-rda/Kconfig b/arch/arm/mach-rda/Kconfig
> index 29012bc68ca4..1ea753f57b2d 100644
> --- a/arch/arm/mach-rda/Kconfig
> +++ b/arch/arm/mach-rda/Kconfig
> @@ -4,5 +4,6 @@ menuconfig ARCH_RDA
> select COMMON_CLK
> select GENERIC_IRQ_CHIP
> select RDA_INTC
> + select RDA_TIMER
> help
> This enables support for the RDA Micro 8810PL SoC family.
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 55c77e44bb2d..f51eee3a72ea 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -105,6 +105,13 @@ config OWL_TIMER
> help
> Enables the support for the Actions Semi Owl timer driver.
>
> +config RDA_TIMER
> + bool "RDA timer driver" if COMPILE_TEST
> + depends on GENERIC_CLOCKEVENTS
> + select CLKSRC_MMIO
> + help
> + Enables the support for the RDA Micro timer driver.
> +
> config SUN4I_TIMER
> bool "Sun4i timer driver" if COMPILE_TEST
> depends on HAS_IOMEM
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index dd9138104568..150020a90707 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -57,6 +57,7 @@ obj-$(CONFIG_OXNAS_RPS_TIMER) += timer-oxnas-rps.o
> obj-$(CONFIG_OWL_TIMER) += timer-owl.o
> obj-$(CONFIG_SPRD_TIMER) += timer-sprd.o
> obj-$(CONFIG_NPCM7XX_TIMER) += timer-npcm7xx.o
> +obj-$(CONFIG_RDA_TIMER) += timer-rda.o
>
> obj-$(CONFIG_ARC_TIMERS) += arc_timer.o
> obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
> diff --git a/drivers/clocksource/timer-rda.c b/drivers/clocksource/timer-rda.c
> new file mode 100644
> index 000000000000..3aa684d92c5d
> --- /dev/null
> +++ b/drivers/clocksource/timer-rda.c
> @@ -0,0 +1,187 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * RDA8810PL SoC timer driver
> + *
> + * Copyright RDA Microelectronics Company Limited
> + * Copyright (c) 2017 Andreas FÃrber
> + * Copyright (c) 2018 Manivannan Sadhasivam
> + */
> +
> +#include <linux/clockchips.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqreturn.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +
> +#define RDA_OSTIMER_LOADVAL_L 0x000
> +#define RDA_OSTIMER_CTRL 0x004
> +#define RDA_HWTIMER_LOCKVAL_L 0x024
> +#define RDA_HWTIMER_LOCKVAL_H 0x028
> +#define RDA_TIMER_IRQ_MASK_SET 0x02c
> +#define RDA_TIMER_IRQ_CLR 0x034
> +
> +#define RDA_OSTIMER_CTRL_ENABLE BIT(24)
> +#define RDA_OSTIMER_CTRL_REPEAT BIT(28)
> +#define RDA_OSTIMER_CTRL_LOAD BIT(30)
> +
> +#define RDA_TIMER_IRQ_MASK_SET_OSTIMER BIT(0)
> +
> +#define RDA_TIMER_IRQ_CLR_OSTIMER BIT(0)
> +
> +static void __iomem *rda_timer_base;
> +
> +static u64 rda_hwtimer_read(struct clocksource *cs)
> +{
> + u32 lo, hi;
> +
> + /* Always read low 32 bits first */
> + lo = readl(rda_timer_base + RDA_HWTIMER_LOCKVAL_L);
> + hi = readl(rda_timer_base + RDA_HWTIMER_LOCKVAL_H);
Please use the relaxed accessors throughout this driver. There is zero
reason to use the non-relaxed versions here.
Now, I'm pretty sure this thing isn't correct.
<timer = 0x00000000ffffffff>
lo = 0xffffffff;
<tick, timer = 0x0000000100000000>
hi = 0x00000001;
Bingo. You cannot read a 64bit counter with only two 32bit accesses.
> +
> + return ((u64)hi << 32) | lo;
> +}
> +
> +static struct clocksource rda_clocksource = {
> + .name = "rda-timer",
> + .rating = 400,
> + .read = rda_hwtimer_read,
> + .mask = CLOCKSOURCE_MASK(64),
This is a 64bit counter? See below.
> + .flags = CLOCK_SOURCE_IS_CONTINUOUS,
> +};
> +
> +static int rda_ostimer_start(bool periodic, u64 cycles)
> +{
> + u32 ctrl, load_l;
> +
> + load_l = (u32)cycles;
> + ctrl = ((cycles >> 32) & 0xffffff);
> + ctrl |= RDA_OSTIMER_CTRL_LOAD | RDA_OSTIMER_CTRL_ENABLE;
> + if (periodic)
> + ctrl |= RDA_OSTIMER_CTRL_REPEAT;
> +
> + /* Enable ostimer interrupt first */
> + writel(RDA_TIMER_IRQ_MASK_SET_OSTIMER,
> + rda_timer_base + RDA_TIMER_IRQ_MASK_SET);
Is it masking or enabling the interrupt?
> +
> + /* Write low 32 bits first, high 24 bits are with ctrl */
You're saying that you can only write 56 bits? This contradicts the 64bt
counter thing above.
> + writel(load_l, rda_timer_base + RDA_OSTIMER_LOADVAL_L);
> + writel(ctrl, rda_timer_base + RDA_OSTIMER_CTRL);
> +
> + return 0;
> +}
> +
> +static int rda_ostimer_stop(void)
> +{
> + /* Disable ostimer interrupt first */
> + writel(0, rda_timer_base + RDA_TIMER_IRQ_MASK_SET);
> +
> + writel(0, rda_timer_base + RDA_OSTIMER_CTRL);
> +
> + return 0;
> +}
> +
> +static int rda_ostimer_set_state_shutdown(struct clock_event_device *evt)
> +{
> + rda_ostimer_stop();
> +
> + return 0;
> +}
> +
> +static int rda_ostimer_set_state_oneshot(struct clock_event_device *evt)
> +{
> + rda_ostimer_stop();
> +
> + return 0;
> +}
> +
> +static int rda_ostimer_set_state_periodic(struct clock_event_device *evt)
> +{
> + unsigned long cycles_per_jiffy;
> +
> + rda_ostimer_stop();
> +
> + cycles_per_jiffy = ((unsigned long long)NSEC_PER_SEC / HZ *
> + evt->mult) >> evt->shift;
> + rda_ostimer_start(true, cycles_per_jiffy);
> +
> + return 0;
> +}
> +
> +static int rda_ostimer_tick_resume(struct clock_event_device *evt)
> +{
> + return 0;
> +}
> +
> +static int rda_ostimer_set_next_event(unsigned long evt,
> + struct clock_event_device *ev)
> +{
> + rda_ostimer_start(false, evt);
> +
> + return 0;
> +}
> +
> +static struct clock_event_device rda_clockevent = {
> + .name = "rda-ostimer",
> + .rating = 250,
> + .features = CLOCK_EVT_FEAT_PERIODIC |
> + CLOCK_EVT_FEAT_ONESHOT |
> + CLOCK_EVT_FEAT_DYNIRQ,
> + .set_state_shutdown = rda_ostimer_set_state_shutdown,
> + .set_state_oneshot = rda_ostimer_set_state_oneshot,
> + .set_state_periodic = rda_ostimer_set_state_periodic,
> + .tick_resume = rda_ostimer_tick_resume,
> + .set_next_event = rda_ostimer_set_next_event,
> +};
> +
> +static irqreturn_t rda_ostimer_interrupt(int irq, void *dev_id)
> +{
> + struct clock_event_device *evt = dev_id;
> +
> + /* clear timer int */
> + writel(RDA_TIMER_IRQ_CLR_OSTIMER, rda_timer_base + RDA_TIMER_IRQ_CLR);
> +
> + if (evt->event_handler)
> + evt->event_handler(evt);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int __init rda_timer_init(struct device_node *node)
> +{
> + unsigned long rate = 2000000;
> + int ostimer_irq, ret;
> +
> + rda_timer_base = of_io_request_and_map(node, 0, "rda-timer");
> + if (IS_ERR(rda_timer_base)) {
> + pr_err("Can't map timer registers");
> + return PTR_ERR(rda_timer_base);
> + }
> +
> + ostimer_irq = of_irq_get_byname(node, "ostimer");
> + if (ostimer_irq <= 0) {
> + pr_err("Can't parse ostimer IRQ");
> + return -EINVAL;
Leaking IO space.
> + }
> +
> + clocksource_register_hz(&rda_clocksource, rate);
> +
> + ret = request_irq(ostimer_irq, rda_ostimer_interrupt, IRQF_TIMER,
> + "rda-ostimer", &rda_clockevent);
> + if (ret) {
> + pr_err("failed to request irq %d\n", ostimer_irq);
> + return ret;
Same here.
> + }
> +
> + irq_force_affinity(ostimer_irq, cpumask_of(0));
Why?
> +
> + rda_clockevent.cpumask = cpumask_of(0);
> + rda_clockevent.irq = ostimer_irq;
> + clockevents_config_and_register(&rda_clockevent, rate,
> + 0x2, 0xffffffff);
> +
> + return 0;
> +}
> +
> +TIMER_OF_DECLARE(rda8810pl, "rda,8810pl-timer", rda_timer_init);
>
Thanks,
M.
--
Jazz is not dead. It just smells funny...