* Tony Lindgren <tony@xxxxxxxxxxx> [080328 13:47]:
> ARM: OMAP: Use posted mode for dmtimer
>
> This patch adds the use of write posting for the timer. Previously, every
> write could lock the requestor for almost 3x32KHz cycles. This patch only
> synchronizes before writes and reads instead of after them and it does
> it on per register basis. Doing it this way there is some chance to hide
> some of the sync latency. It also removes some needless reads when
> non-posted mode is there. With out this fix the read/writes take almost
> 2% CPU load @500MHz just waiting on tick timer registers.
>
> Also define new 34xx only registers.
Please ignore this patch too.
Tony
>
> Signed-off-by: Richard Woodruff <r-woodruff2@xxxxxx>
> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
>
> --- a/arch/arm/plat-omap/dmtimer.c
> +++ b/arch/arm/plat-omap/dmtimer.c
> @@ -38,34 +38,113 @@
> #include <asm/arch/irqs.h>
>
> /* register offsets */
> -#define OMAP_TIMER_ID_REG 0x00
> -#define OMAP_TIMER_OCP_CFG_REG 0x10
> -#define OMAP_TIMER_SYS_STAT_REG 0x14
> -#define OMAP_TIMER_STAT_REG 0x18
> -#define OMAP_TIMER_INT_EN_REG 0x1c
> -#define OMAP_TIMER_WAKEUP_EN_REG 0x20
> -#define OMAP_TIMER_CTRL_REG 0x24
> -#define OMAP_TIMER_COUNTER_REG 0x28
> -#define OMAP_TIMER_LOAD_REG 0x2c
> -#define OMAP_TIMER_TRIGGER_REG 0x30
> -#define OMAP_TIMER_WRITE_PEND_REG 0x34
> -#define OMAP_TIMER_MATCH_REG 0x38
> -#define OMAP_TIMER_CAPTURE_REG 0x3c
> -#define OMAP_TIMER_IF_CTRL_REG 0x40
> -
> -/* timer control reg bits */
> -#define OMAP_TIMER_CTRL_GPOCFG (1 << 14)
> -#define OMAP_TIMER_CTRL_CAPTMODE (1 << 13)
> -#define OMAP_TIMER_CTRL_PT (1 << 12)
> -#define OMAP_TIMER_CTRL_TCM_LOWTOHIGH (0x1 << 8)
> -#define OMAP_TIMER_CTRL_TCM_HIGHTOLOW (0x2 << 8)
> -#define OMAP_TIMER_CTRL_TCM_BOTHEDGES (0x3 << 8)
> -#define OMAP_TIMER_CTRL_SCPWM (1 << 7)
> -#define OMAP_TIMER_CTRL_CE (1 << 6) /* compare enable */
> -#define OMAP_TIMER_CTRL_PRE (1 << 5) /* prescaler enable */
> -#define OMAP_TIMER_CTRL_PTV_SHIFT 2 /* how much to shift the prescaler value */
> -#define OMAP_TIMER_CTRL_AR (1 << 1) /* auto-reload enable */
> -#define OMAP_TIMER_CTRL_ST (1 << 0) /* start timer */
> +#define _OMAP_TIMER_ID_OFFSET 0x00
> +#define _OMAP_TIMER_OCP_CFG_OFFSET 0x10
> +#define _OMAP_TIMER_SYS_STAT_OFFSET 0x14
> +#define _OMAP_TIMER_STAT_OFFSET 0x18
> +#define _OMAP_TIMER_INT_EN_OFFSET 0x1c
> +#define _OMAP_TIMER_WAKEUP_EN_OFFSET 0x20
> +#define _OMAP_TIMER_CTRL_OFFSET 0x24
> +#define OMAP_TIMER_CTRL_GPOCFG (1 << 14)
> +#define OMAP_TIMER_CTRL_CAPTMODE (1 << 13)
> +#define OMAP_TIMER_CTRL_PT (1 << 12)
> +#define OMAP_TIMER_CTRL_TCM_LOWTOHIGH (0x1 << 8)
> +#define OMAP_TIMER_CTRL_TCM_HIGHTOLOW (0x2 << 8)
> +#define OMAP_TIMER_CTRL_TCM_BOTHEDGES (0x3 << 8)
> +#define OMAP_TIMER_CTRL_SCPWM (1 << 7)
> +#define OMAP_TIMER_CTRL_CE (1 << 6) /* compare enable */
> +#define OMAP_TIMER_CTRL_PRE (1 << 5) /* prescaler enable */
> +#define OMAP_TIMER_CTRL_PTV_SHIFT 2 /* prescaler value shift */
> +#define OMAP_TIMER_CTRL_POSTED (1 << 2)
> +#define OMAP_TIMER_CTRL_AR (1 << 1) /* auto-reload enable */
> +#define OMAP_TIMER_CTRL_ST (1 << 0) /* start timer */
> +#define _OMAP_TIMER_COUNTER_OFFSET 0x28
> +#define _OMAP_TIMER_LOAD_OFFSET 0x2c
> +#define _OMAP_TIMER_TRIGGER_OFFSET 0x30
> +#define _OMAP_TIMER_WRITE_PEND_OFFSET 0x34
> +#define WP_NONE 0 /* no write pending bit */
> +#define WP_TCLR (1 << 0)
> +#define WP_TCRR (1 << 1)
> +#define WP_TLDR (1 << 2)
> +#define WP_TTGR (1 << 3)
> +#define WP_TMAR (1 << 4)
> +#define WP_TPIR (1 << 5)
> +#define WP_TNIR (1 << 6)
> +#define WP_TCVR (1 << 7)
> +#define WP_TOCR (1 << 8)
> +#define WP_TOWR (1 << 9)
> +#define _OMAP_TIMER_MATCH_OFFSET 0x38
> +#define _OMAP_TIMER_CAPTURE_OFFSET 0x3c
> +#define _OMAP_TIMER_IF_CTRL_OFFSET 0x40
> +#define _OMAP_TIMER_CAPTURE2_OFFSET 0x44 /* TCAR2, 34xx only */
> +#define _OMAP_TIMER_TICK_POS_OFFSET 0x48 /* TPIR, 34xx only */
> +#define _OMAP_TIMER_TICK_NEG_OFFSET 0x4c /* TNIR, 34xx only */
> +#define _OMAP_TIMER_TICK_COUNT_OFFSET 0x50 /* TCVR, 34xx only */
> +#define _OMAP_TIMER_TICK_INT_MASK_SET_OFFSET 0x54 /* TOCR, 34xx only */
> +#define _OMAP_TIMER_TICK_INT_MASK_COUNT_OFFSET 0x58 /* TOWR, 34xx only */
> +
> +/* register offsets with the write pending bit encoded */
> +#define WPSHIFT 16
> +
> +#define OMAP_TIMER_ID_REG (_OMAP_TIMER_ID_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_OCP_CFG_REG (_OMAP_TIMER_OCP_CFG_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_SYS_STAT_REG (_OMAP_TIMER_SYS_STAT_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_STAT_REG (_OMAP_TIMER_STAT_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_INT_EN_REG (_OMAP_TIMER_INT_EN_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_WAKEUP_EN_REG (_OMAP_TIMER_WAKEUP_EN_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_CTRL_REG (_OMAP_TIMER_CTRL_OFFSET \
> + | (WP_TCLR << WPSHIFT))
> +
> +#define OMAP_TIMER_COUNTER_REG (_OMAP_TIMER_COUNTER_OFFSET \
> + | (WP_TCRR << WPSHIFT))
> +
> +#define OMAP_TIMER_LOAD_REG (_OMAP_TIMER_LOAD_OFFSET \
> + | (WP_TLDR << WPSHIFT))
> +
> +#define OMAP_TIMER_TRIGGER_REG (_OMAP_TIMER_TRIGGER_OFFSET \
> + | (WP_TTGR << WPSHIFT))
> +
> +#define OMAP_TIMER_WRITE_PEND_REG (_OMAP_TIMER_WRITE_PEND_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_MATCH_REG (_OMAP_TIMER_MATCH_OFFSET \
> + | (WP_TMAR << WPSHIFT))
> +
> +#define OMAP_TIMER_CAPTURE_REG (_OMAP_TIMER_CAPTURE_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_IF_CTRL_REG (_OMAP_TIMER_IF_CTRL_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_CAPTURE2_REG (_OMAP_TIMER_CAPTURE2_OFFSET \
> + | (WP_NONE << WPSHIFT))
> +
> +#define OMAP_TIMER_TICK_POS_REG (_OMAP_TIMER_TICK_POS_OFFSET \
> + | (WP_TPIR << WPSHIFT))
> +
> +#define OMAP_TIMER_TICK_NEG_REG (_OMAP_TIMER_TICK_NEG_OFFSET \
> + | (WP_TNIR << WPSHIFT))
> +
> +#define OMAP_TIMER_TICK_COUNT_REG (_OMAP_TIMER_TICK_COUNT_OFFSET \
> + | (WP_TCVR << WPSHIFT))
> +
> +#define OMAP_TIMER_TICK_INT_MASK_SET_REG \
> + (_OMAP_TIMER_TICK_INT_MASK_SET_OFFSET | (WP_TOCR << WPSHIFT))
> +
> +#define OMAP_TIMER_TICK_INT_MASK_COUNT_REG \
> + (_OMAP_TIMER_TICK_INT_MASK_COUNT_OFFSET | (WP_TOWR << WPSHIFT))
>
> struct omap_dm_timer {
> unsigned long phys_base;
> @@ -76,6 +155,7 @@ struct omap_dm_timer {
> void __iomem *io_base;
> unsigned reserved:1;
> unsigned enabled:1;
> + unsigned posted:1;
> };
>
> #ifdef CONFIG_ARCH_OMAP1
> @@ -181,16 +261,34 @@ static struct clk **dm_source_clocks;
>
> static spinlock_t dm_timer_lock;
>
> -static inline u32 omap_dm_timer_read_reg(struct omap_dm_timer *timer, int reg)
> +/*
> + * Reads timer registers in posted and non-posted mode. The posted mode bit
> + * is encoded in reg. Note that in posted mode write pending bit must be
> + * checked. Otherwise a read of a non completed write will produce an error.
> + */
> +static inline u32 omap_dm_timer_read_reg(struct omap_dm_timer *timer, u32 reg)
> {
> - return readl(timer->io_base + reg);
> + if (timer->posted)
> + while (readl(timer->io_base + (OMAP_TIMER_WRITE_PEND_REG & 0xff))
> + & (reg >> WPSHIFT))
> + cpu_relax();
> + return readl(timer->io_base + (reg & 0xff));
> }
>
> -static void omap_dm_timer_write_reg(struct omap_dm_timer *timer, int reg, u32 value)
> +/*
> + * Writes timer registers in posted and non-posted mode. The posted mode bit
> + * is encoded in reg. Note that in posted mode the write pending bit must be
> + * checked. Otherwise a write on a register which has a pending write will be
> + * lost.
> + */
> +static void omap_dm_timer_write_reg(struct omap_dm_timer *timer, u32 reg,
> + u32 value)
> {
> - writel(value, timer->io_base + reg);
> - while (omap_dm_timer_read_reg(timer, OMAP_TIMER_WRITE_PEND_REG))
> - ;
> + if (timer->posted)
> + while (readl(timer->io_base + (OMAP_TIMER_WRITE_PEND_REG & 0xff))
> + & (reg >> WPSHIFT))
> + cpu_relax();
> + writel(value, timer->io_base + (reg & 0xff));
> }
>
> static void omap_dm_timer_wait_for_reset(struct omap_dm_timer *timer)
> @@ -217,17 +315,23 @@ static void omap_dm_timer_reset(struct omap_dm_timer *timer)
> }
> omap_dm_timer_set_source(timer, OMAP_TIMER_SRC_32_KHZ);
>
> - /* Set to smart-idle mode */
> l = omap_dm_timer_read_reg(timer, OMAP_TIMER_OCP_CFG_REG);
> - l |= 0x02 << 3;
> -
> - if (cpu_class_is_omap2() && timer == &dm_timers[0]) {
> - /* Enable wake-up only for GPT1 on OMAP2 CPUs*/
> + l |= 0x02 << 3; /* Set to smart-idle mode */
> + l |= 0x2 << 8; /* Set clock activity to perserve f-clock on idle */
> +
> + /*
> + * Enable wake-up only for GPT1 on OMAP2 CPUs.
> + * FIXME: All timers should have wake-up enabled and clear
> + * PRCM status.
> + */
> + if (cpu_class_is_omap2() && (timer == &dm_timers[0]))
> l |= 1 << 2;
> - /* Non-posted mode */
> - omap_dm_timer_write_reg(timer, OMAP_TIMER_IF_CTRL_REG, 0);
> - }
> omap_dm_timer_write_reg(timer, OMAP_TIMER_OCP_CFG_REG, l);
> +
> + /* Match hardware reset default of posted mode */
> + omap_dm_timer_write_reg(timer, OMAP_TIMER_IF_CTRL_REG,
> + OMAP_TIMER_CTRL_POSTED);
> + timer->posted = 1;
> }
>
> static void omap_dm_timer_prepare(struct omap_dm_timer *timer)
> @@ -434,6 +538,11 @@ void omap_dm_timer_set_load(struct omap_dm_timer *timer, int autoreload,
> l &= ~OMAP_TIMER_CTRL_AR;
> omap_dm_timer_write_reg(timer, OMAP_TIMER_CTRL_REG, l);
> omap_dm_timer_write_reg(timer, OMAP_TIMER_LOAD_REG, load);
> +
> + /* REVISIT: hw feature, ttgr overtaking tldr? */
> + while (readl(timer->io_base + (OMAP_TIMER_WRITE_PEND_REG & 0xff)))
> + cpu_relax();
> +
> omap_dm_timer_write_reg(timer, OMAP_TIMER_TRIGGER_REG, 0);
> }
>
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
