Hi Marc,
On Mon, Nov 19, 2018 at 05:57:12PM +0000, Marc Zyngier wrote:
> 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 Färber <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 Färber
> > + * 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.
>
Okay.
> 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.
>
I think the lack of description makes confusion here. In this SoC, there
are two independent timers available: OSTIMER (56 bit) and HWTIMER (64 bit)
with optional interrupt support. I have used OSTIMER for clockevents and
HWTIMER for clocksource. Will add this information in driver.
Please let me know whether I have to model these two clocksources
differently!
> > +
> > + 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.
>
Yes, this is the HWTIMER and is 64 bit.
> > + .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?
>
On this platform, we need to set corresponding bit in the RDA_TIMER_IRQ_MASK_SET
register to enable an 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);
> > +
Here the register should be RDA_TIMER_IRQ_MASK_CLR.
> > + 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.
>
Ack.
> > + }
> > +
> > + 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.
>
Ack.
> > + }
> > +
> > + irq_force_affinity(ostimer_irq, cpumask_of(0));
>
> Why?
>
Not needed, will remove it.
Thanks,
Mani
> > +
> > + 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...
