Re: [PATCH 7/8] clocksource/drivers/fttmr010: Merge Moxa into FTTMR010

[Joel Stanley]

Hey Linus,

On Wed, May 17, 2017 at 10:05 PM, Linus Walleij
<linus.walleij@xxxxxxxxxx> wrote:
> This merges the Moxa Art timer driver into the Faraday FTTMR010
> driver and replaces all Kconfig symbols to use the Faraday
> driver instead. We are now so similar that the drivers can
> be merged by just adding a few lines to the Faraday timer.

Nice work!

I gave this a spin on hardware and it didn't work :(

>
> Differences:
>
> - The Faraday driver explicitly sets the counter to count
>   upwards for the clocksource, removing the need for the
>   clocksource core to invert the value.
>
> - The Faraday driver also handles sched_clock()
>
> I am just guessing at the way the Aspeed has moved the count
> up/down bits to bits 3, 8 and 11 (keeping the bits pertaining
> to a certain timer together), so this really needs testing on
> the Aspeed. I'm guessing like this because it is what I would
> have done, if I was rewriting some VHDL/Verilog to extend
> these three timers to 8 (as the Aspeed apparently does).
>
> After this we have one driver for all three SoCs and a generic
> Faraday FTTMR010 timer driver, which is nice.
>
> Cc: Joel Stanley <joel@xxxxxxxxx>
> Cc: Jonas Jensen <jonas.jensen@xxxxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
> ARM SoC folks: please ACK this so it can be merged with in the
> clocksource subsystem once it works.
>
> Joel: it would be super if you can test this. If you have some
> vendor tree or similar that actually indicates where the
> up/down counter bits are it's even better, but I'm hoping that
> this half-assed guesswork will JustWork(TM) (yeah, famous
> last words, sorry...)

Thanks for the rework! Unfortunately the Aspeed IP does not have bits
to control the direction of counting, and the timers only count down.
Bits 3, 7 and 11 are marked reserved in the data sheet. Can you rework
the patch to count down?

As an aside, we have a pretty decent model for the Aspeed SoCs in
Qemu. If you want to use it to smoketest your rework:

 $ qemu-system-arm -m 512 -M ast2500-evb -nodefaults -nographic
-serial stdio -kernel arch/arm/boot/zImage -dtb
arch/arm/boot/dts/aspeed-ast2500-evb.dtb

I tested with Ubuntu's qemu v2.8. It looks like we have a bug when the
kernel tries to use the clock the way your driver works, so we will
look at that. It does function properly for the current upstream code.

Cheers,

Joel

> ---
>  arch/arm/mach-aspeed/Kconfig         |   2 +-
>  arch/arm/mach-moxart/Kconfig         |   2 +-
>  drivers/clocksource/Kconfig          |   7 -
>  drivers/clocksource/Makefile         |   1 -
>  drivers/clocksource/moxart_timer.c   | 256 -----------------------------------
>  drivers/clocksource/timer-fttmr010.c |  52 +++++--
>  6 files changed, 46 insertions(+), 274 deletions(-)
>  delete mode 100644 drivers/clocksource/moxart_timer.c
>
> diff --git a/arch/arm/mach-aspeed/Kconfig b/arch/arm/mach-aspeed/Kconfig
> index f3f8c5c658db..2d5570e6e186 100644
> --- a/arch/arm/mach-aspeed/Kconfig
> +++ b/arch/arm/mach-aspeed/Kconfig
> @@ -4,7 +4,7 @@ menuconfig ARCH_ASPEED
>         select SRAM
>         select WATCHDOG
>         select ASPEED_WATCHDOG
> -       select MOXART_TIMER
> +       select FTTMR010_TIMER
>         select MFD_SYSCON
>         select PINCTRL
>         help
> diff --git a/arch/arm/mach-moxart/Kconfig b/arch/arm/mach-moxart/Kconfig
> index 70db2abf6163..a4a91f9a3301 100644
> --- a/arch/arm/mach-moxart/Kconfig
> +++ b/arch/arm/mach-moxart/Kconfig
> @@ -4,7 +4,7 @@ menuconfig ARCH_MOXART
>         select CPU_FA526
>         select ARM_DMA_MEM_BUFFERABLE
>         select FARADAY_FTINTC010
> -       select MOXART_TIMER
> +       select FTTMR010_TIMER
>         select GPIOLIB
>         select PHYLIB if NETDEVICES
>         help
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 545d541ae20e..1b22ade4c8f1 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -188,13 +188,6 @@ config ATLAS7_TIMER
>         help
>           Enables support for the Atlas7 timer.
>
> -config MOXART_TIMER
> -       bool "Moxart timer driver" if COMPILE_TEST
> -       depends on GENERIC_CLOCKEVENTS
> -       select CLKSRC_MMIO
> -       help
> -         Enables support for the Moxart timer.
> -
>  config MXS_TIMER
>         bool "Mxs timer driver" if COMPILE_TEST
>         depends on GENERIC_CLOCKEVENTS
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 2b5b56a6f00f..cf0c30b6ec1f 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -26,7 +26,6 @@ obj-$(CONFIG_ORION_TIMER)     += time-orion.o
>  obj-$(CONFIG_BCM2835_TIMER)    += bcm2835_timer.o
>  obj-$(CONFIG_CLPS711X_TIMER)   += clps711x-timer.o
>  obj-$(CONFIG_ATLAS7_TIMER)     += timer-atlas7.o
> -obj-$(CONFIG_MOXART_TIMER)     += moxart_timer.o
>  obj-$(CONFIG_MXS_TIMER)                += mxs_timer.o
>  obj-$(CONFIG_CLKSRC_PXA)       += pxa_timer.o
>  obj-$(CONFIG_PRIMA2_TIMER)     += timer-prima2.o
> diff --git a/drivers/clocksource/moxart_timer.c b/drivers/clocksource/moxart_timer.c
> deleted file mode 100644
> index 7f3430654fbd..000000000000
> --- a/drivers/clocksource/moxart_timer.c
> +++ /dev/null
> @@ -1,256 +0,0 @@
> -/*
> - * MOXA ART SoCs timer handling.
> - *
> - * Copyright (C) 2013 Jonas Jensen
> - *
> - * Jonas Jensen <jonas.jensen@xxxxxxxxx>
> - *
> - * This file is licensed under the terms of the GNU General Public
> - * License version 2.  This program is licensed "as is" without any
> - * warranty of any kind, whether express or implied.
> - */
> -
> -#include <linux/clk.h>
> -#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>
> -#include <linux/io.h>
> -#include <linux/clocksource.h>
> -#include <linux/bitops.h>
> -#include <linux/slab.h>
> -
> -#define TIMER1_BASE            0x00
> -#define TIMER2_BASE            0x10
> -#define TIMER3_BASE            0x20
> -
> -#define REG_COUNT              0x0 /* writable */
> -#define REG_LOAD               0x4
> -#define REG_MATCH1             0x8
> -#define REG_MATCH2             0xC
> -
> -#define TIMER_CR               0x30
> -#define TIMER_INTR_STATE       0x34
> -#define TIMER_INTR_MASK                0x38
> -
> -/*
> - * Moxart TIMER_CR flags:
> - *
> - * MOXART_CR_*_CLOCK   0: PCLK, 1: EXT1CLK
> - * MOXART_CR_*_INT     overflow interrupt enable bit
> - */
> -#define MOXART_CR_1_ENABLE     BIT(0)
> -#define MOXART_CR_1_CLOCK      BIT(1)
> -#define MOXART_CR_1_INT        BIT(2)
> -#define MOXART_CR_2_ENABLE     BIT(3)
> -#define MOXART_CR_2_CLOCK      BIT(4)
> -#define MOXART_CR_2_INT        BIT(5)
> -#define MOXART_CR_3_ENABLE     BIT(6)
> -#define MOXART_CR_3_CLOCK      BIT(7)
> -#define MOXART_CR_3_INT        BIT(8)
> -#define MOXART_CR_COUNT_UP     BIT(9)
> -
> -#define MOXART_TIMER1_ENABLE   (MOXART_CR_2_ENABLE | MOXART_CR_1_ENABLE)
> -#define MOXART_TIMER1_DISABLE  (MOXART_CR_2_ENABLE)
> -
> -/*
> - * The ASpeed variant of the IP block has a different layout
> - * for the control register
> - */
> -#define ASPEED_CR_1_ENABLE     BIT(0)
> -#define ASPEED_CR_1_CLOCK      BIT(1)
> -#define ASPEED_CR_1_INT                BIT(2)
> -#define ASPEED_CR_2_ENABLE     BIT(4)
> -#define ASPEED_CR_2_CLOCK      BIT(5)
> -#define ASPEED_CR_2_INT                BIT(6)
> -#define ASPEED_CR_3_ENABLE     BIT(8)
> -#define ASPEED_CR_3_CLOCK      BIT(9)
> -#define ASPEED_CR_3_INT                BIT(10)
> -
> -#define ASPEED_TIMER1_ENABLE   (ASPEED_CR_2_ENABLE | ASPEED_CR_1_ENABLE)
> -#define ASPEED_TIMER1_DISABLE  (ASPEED_CR_2_ENABLE)
> -
> -struct moxart_timer {
> -       void __iomem *base;
> -       unsigned int t1_disable_val;
> -       unsigned int t1_enable_val;
> -       unsigned int count_per_tick;
> -       struct clock_event_device clkevt;
> -};
> -
> -static inline struct moxart_timer *to_moxart(struct clock_event_device *evt)
> -{
> -       return container_of(evt, struct moxart_timer, clkevt);
> -}
> -
> -static inline void moxart_disable(struct clock_event_device *evt)
> -{
> -       struct moxart_timer *timer = to_moxart(evt);
> -
> -       writel(timer->t1_disable_val, timer->base + TIMER_CR);
> -}
> -
> -static inline void moxart_enable(struct clock_event_device *evt)
> -{
> -       struct moxart_timer *timer = to_moxart(evt);
> -
> -       writel(timer->t1_enable_val, timer->base + TIMER_CR);
> -}
> -
> -static int moxart_shutdown(struct clock_event_device *evt)
> -{
> -       moxart_disable(evt);
> -       return 0;
> -}
> -
> -static int moxart_set_oneshot(struct clock_event_device *evt)
> -{
> -       moxart_disable(evt);
> -       writel(~0, to_moxart(evt)->base + TIMER1_BASE + REG_LOAD);
> -       return 0;
> -}
> -
> -static int moxart_set_periodic(struct clock_event_device *evt)
> -{
> -       struct moxart_timer *timer = to_moxart(evt);
> -
> -       moxart_disable(evt);
> -       writel(timer->count_per_tick, timer->base + TIMER1_BASE + REG_LOAD);
> -       writel(0, timer->base + TIMER1_BASE + REG_MATCH1);
> -       moxart_enable(evt);
> -       return 0;
> -}
> -
> -static int moxart_clkevt_next_event(unsigned long cycles,
> -                                   struct clock_event_device *evt)
> -{
> -       struct moxart_timer *timer = to_moxart(evt);
> -       u32 u;
> -
> -       moxart_disable(evt);
> -
> -       u = readl(timer->base + TIMER1_BASE + REG_COUNT) - cycles;
> -       writel(u, timer->base + TIMER1_BASE + REG_MATCH1);
> -
> -       moxart_enable(evt);
> -
> -       return 0;
> -}
> -
> -static irqreturn_t moxart_timer_interrupt(int irq, void *dev_id)
> -{
> -       struct clock_event_device *evt = dev_id;
> -       evt->event_handler(evt);
> -       return IRQ_HANDLED;
> -}
> -
> -static int __init moxart_timer_init(struct device_node *node)
> -{
> -       int ret, irq;
> -       unsigned long pclk;
> -       struct clk *clk;
> -       struct moxart_timer *timer;
> -
> -       timer = kzalloc(sizeof(*timer), GFP_KERNEL);
> -       if (!timer)
> -               return -ENOMEM;
> -
> -       timer->base = of_iomap(node, 0);
> -       if (!timer->base) {
> -               pr_err("%s: of_iomap failed\n", node->full_name);
> -               ret = -ENXIO;
> -               goto out_free;
> -       }
> -
> -       irq = irq_of_parse_and_map(node, 0);
> -       if (irq <= 0) {
> -               pr_err("%s: irq_of_parse_and_map failed\n", node->full_name);
> -               ret = -EINVAL;
> -               goto out_unmap;
> -       }
> -
> -       clk = of_clk_get(node, 0);
> -       if (IS_ERR(clk))  {
> -               pr_err("%s: of_clk_get failed\n", node->full_name);
> -               ret = PTR_ERR(clk);
> -               goto out_unmap;
> -       }
> -
> -       pclk = clk_get_rate(clk);
> -
> -       if (of_device_is_compatible(node, "moxa,moxart-timer")) {
> -               timer->t1_enable_val = MOXART_TIMER1_ENABLE;
> -               timer->t1_disable_val = MOXART_TIMER1_DISABLE;
> -       } else if (of_device_is_compatible(node, "aspeed,ast2400-timer")) {
> -               timer->t1_enable_val = ASPEED_TIMER1_ENABLE;
> -               timer->t1_disable_val = ASPEED_TIMER1_DISABLE;
> -       } else {
> -               pr_err("%s: unknown platform\n", node->full_name);
> -               ret = -EINVAL;
> -               goto out_unmap;
> -       }
> -
> -       timer->count_per_tick = DIV_ROUND_CLOSEST(pclk, HZ);
> -
> -       timer->clkevt.name = node->name;
> -       timer->clkevt.rating = 200;
> -       timer->clkevt.features = CLOCK_EVT_FEAT_PERIODIC |
> -                                       CLOCK_EVT_FEAT_ONESHOT;
> -       timer->clkevt.set_state_shutdown = moxart_shutdown;
> -       timer->clkevt.set_state_periodic = moxart_set_periodic;
> -       timer->clkevt.set_state_oneshot = moxart_set_oneshot;
> -       timer->clkevt.tick_resume = moxart_set_oneshot;
> -       timer->clkevt.set_next_event = moxart_clkevt_next_event;
> -       timer->clkevt.cpumask = cpumask_of(0);
> -       timer->clkevt.irq = irq;
> -
> -       ret = clocksource_mmio_init(timer->base + TIMER2_BASE + REG_COUNT,
> -                                   "moxart_timer", pclk, 200, 32,
> -                                   clocksource_mmio_readl_down);
> -       if (ret) {
> -               pr_err("%s: clocksource_mmio_init failed\n", node->full_name);
> -               goto out_unmap;
> -       }
> -
> -       ret = request_irq(irq, moxart_timer_interrupt, IRQF_TIMER,
> -                         node->name, &timer->clkevt);
> -       if (ret) {
> -               pr_err("%s: setup_irq failed\n", node->full_name);
> -               goto out_unmap;
> -       }
> -
> -       /* Clear match registers */
> -       writel(0, timer->base + TIMER1_BASE + REG_MATCH1);
> -       writel(0, timer->base + TIMER1_BASE + REG_MATCH2);
> -       writel(0, timer->base + TIMER2_BASE + REG_MATCH1);
> -       writel(0, timer->base + TIMER2_BASE + REG_MATCH2);
> -
> -       /*
> -        * Start timer 2 rolling as our main wall clock source, keep timer 1
> -        * disabled
> -        */
> -       writel(0, timer->base + TIMER_CR);
> -       writel(~0, timer->base + TIMER2_BASE + REG_LOAD);
> -       writel(timer->t1_disable_val, timer->base + TIMER_CR);
> -
> -       /*
> -        * documentation is not publicly available:
> -        * min_delta / max_delta obtained by trial-and-error,
> -        * max_delta 0xfffffffe should be ok because count
> -        * register size is u32
> -        */
> -       clockevents_config_and_register(&timer->clkevt, pclk, 0x4, 0xfffffffe);
> -
> -       return 0;
> -
> -out_unmap:
> -       iounmap(timer->base);
> -out_free:
> -       kfree(timer);
> -       return ret;
> -}
> -CLOCKSOURCE_OF_DECLARE(moxart, "moxa,moxart-timer", moxart_timer_init);
> -CLOCKSOURCE_OF_DECLARE(aspeed, "aspeed,ast2400-timer", moxart_timer_init);
> diff --git a/drivers/clocksource/timer-fttmr010.c b/drivers/clocksource/timer-fttmr010.c
> index 2d915d1455ab..86d5159d3457 100644
> --- a/drivers/clocksource/timer-fttmr010.c
> +++ b/drivers/clocksource/timer-fttmr010.c
> @@ -50,6 +50,20 @@
>  #define TIMER_2_CR_UPDOWN      BIT(10)
>  #define TIMER_3_CR_UPDOWN      BIT(11)
>
> +/* The Aspeed AST2400 moves bits around in the control register */
> +#define TIMER_1_CR_ASPEED_ENABLE       BIT(0)
> +#define TIMER_1_CR_ASPEED_CLOCK                BIT(1)
> +#define TIMER_1_CR_ASPEED_INT          BIT(2)
> +#define TIMER_1_CR_ASPEED_UPDOWN       BIT(3)
> +#define TIMER_2_CR_ASPEED_ENABLE       BIT(4)
> +#define TIMER_2_CR_ASPEED_CLOCK                BIT(5)
> +#define TIMER_2_CR_ASPEED_INT          BIT(6)
> +#define TIMER_2_CR_ASPEED_UPDOWN       BIT(7)
> +#define TIMER_3_CR_ASPEED_ENABLE       BIT(8)
> +#define TIMER_3_CR_ASPEED_CLOCK                BIT(9)
> +#define TIMER_3_CR_ASPEED_INT          BIT(10)
> +#define TIMER_3_CR_ASPEED_UPDOWN       BIT(11)
> +
>  #define TIMER_1_INT_MATCH1     BIT(0)
>  #define TIMER_1_INT_MATCH2     BIT(1)
>  #define TIMER_1_INT_OVERFLOW   BIT(2)
> @@ -64,6 +78,8 @@
>  struct fttmr010 {
>         void __iomem *base;
>         unsigned int tick_rate;
> +       bool is_ast2400;
> +       u32 t1_enable_val;
>         struct clock_event_device clkevt;
>  };
>
> @@ -102,7 +118,7 @@ static int fttmr010_timer_shutdown(struct clock_event_device *evt)
>
>         /* Stop timer and interrupt. */
>         cr = readl(fttmr010->base + TIMER_CR);
> -       cr &= ~(TIMER_1_CR_ENABLE | TIMER_1_CR_INT);
> +       cr &= ~fttmr010->t1_enable_val;
>         writel(cr, fttmr010->base + TIMER_CR);
>
>         return 0;
> @@ -115,7 +131,7 @@ static int fttmr010_timer_set_oneshot(struct clock_event_device *evt)
>
>         /* Stop timer and interrupt. */
>         cr = readl(fttmr010->base + TIMER_CR);
> -       cr &= ~(TIMER_1_CR_ENABLE | TIMER_1_CR_INT);
> +       cr &= ~fttmr010->t1_enable_val;
>         writel(cr, fttmr010->base + TIMER_CR);
>
>         /* Setup counter start from 0 */
> @@ -130,7 +146,7 @@ static int fttmr010_timer_set_oneshot(struct clock_event_device *evt)
>
>         /* Start the timer */
>         cr = readl(fttmr010->base + TIMER_CR);
> -       cr |= TIMER_1_CR_ENABLE;
> +       cr |= fttmr010->t1_enable_val;
>         writel(cr, fttmr010->base + TIMER_CR);
>
>         return 0;
> @@ -144,7 +160,7 @@ static int fttmr010_timer_set_periodic(struct clock_event_device *evt)
>
>         /* Stop timer and interrupt */
>         cr = readl(fttmr010->base + TIMER_CR);
> -       cr &= ~(TIMER_1_CR_ENABLE | TIMER_1_CR_INT);
> +       cr &= ~fttmr010->t1_enable_val;
>         writel(cr, fttmr010->base + TIMER_CR);
>
>         /* Setup timer to fire at 1/HT intervals. */
> @@ -160,8 +176,7 @@ static int fttmr010_timer_set_periodic(struct clock_event_device *evt)
>
>         /* Start the timer */
>         cr = readl(fttmr010->base + TIMER_CR);
> -       cr |= TIMER_1_CR_ENABLE;
> -       cr |= TIMER_1_CR_INT;
> +       cr |= fttmr010->t1_enable_val;
>         writel(cr, fttmr010->base + TIMER_CR);
>
>         return 0;
> @@ -184,6 +199,7 @@ static int __init fttmr010_timer_init(struct device_node *np)
>         int irq;
>         struct clk *clk;
>         int ret;
> +       u32 val;
>
>         /*
>          * These implementations require a clock reference.
> @@ -223,13 +239,31 @@ static int __init fttmr010_timer_init(struct device_node *np)
>         }
>
>         /*
> +        * The Aspeed AST2400 moves bits around in the control register,
> +        * otherwise it works the same.
> +        */
> +       fttmr010->is_ast2400 =
> +               of_device_is_compatible(np, "aspeed,ast2400-timer");
> +       if (fttmr010->is_ast2400)
> +               fttmr010->t1_enable_val = TIMER_1_CR_ASPEED_ENABLE |
> +                       TIMER_1_CR_ASPEED_INT;
> +       else
> +               fttmr010->t1_enable_val = TIMER_1_CR_ENABLE | TIMER_1_CR_INT;
> +
> +       /*
>          * Reset the interrupt mask and status
>          */
>         writel(TIMER_INT_ALL_MASK, fttmr010->base + TIMER_INTR_MASK);
>         writel(0, fttmr010->base + TIMER_INTR_STATE);
> +
>         /* Enable timer 1 count up, timer 2 count up */
> -       writel((TIMER_1_CR_UPDOWN | TIMER_2_CR_ENABLE | TIMER_2_CR_UPDOWN),
> -              fttmr010->base + TIMER_CR);
> +       if (fttmr010->is_ast2400)
> +               val = TIMER_1_CR_ASPEED_UPDOWN | TIMER_2_CR_ASPEED_ENABLE |
> +                       TIMER_2_CR_ASPEED_UPDOWN;
> +       else
> +               val = TIMER_1_CR_UPDOWN | TIMER_2_CR_ENABLE |
> +                       TIMER_2_CR_UPDOWN;
> +       writel(val, fttmr010->base + TIMER_CR);
>
>         /*
>          * Setup free-running clocksource timer (interrupts
> @@ -290,3 +324,5 @@ static int __init fttmr010_timer_init(struct device_node *np)
>  }
>  CLOCKSOURCE_OF_DECLARE(fttmr010, "faraday,fttmr010", fttmr010_timer_init);
>  CLOCKSOURCE_OF_DECLARE(gemini, "cortina,gemini-timer", fttmr010_timer_init);
> +CLOCKSOURCE_OF_DECLARE(moxart, "moxa,moxart-timer", fttmr010_timer_init);
> +CLOCKSOURCE_OF_DECLARE(aspeed, "aspeed,ast2400-timer", fttmr010_timer_init);
> --
> 2.9.3
>