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authorLinus Walleij <linus.walleij@stericsson.com>2010-09-13 13:40:04 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-09-17 10:16:48 +0100
commita0719f52d90aed5b82ecf2f3ed14bc4ced3d1a8a (patch)
tree2441c3195a1d8d7d70cdbdf6c39381cae5b7cd78
parent99f76891a33d130776da3b01935d978b1e75fe68 (diff)
downloadop-kernel-dev-a0719f52d90aed5b82ecf2f3ed14bc4ced3d1a8a.zip
op-kernel-dev-a0719f52d90aed5b82ecf2f3ed14bc4ced3d1a8a.tar.gz
ARM: 6376/1: plat-nomadik: MTU: Change prescaler limit and comment updates
The prescaler 16 is now used only when the timer runs at 32 MHz or more. Some comment updates as well. Acked-by: Alessandro Rubini <rubini@unipv.it> Signed-off-by: Jonas Aaberg <jonas.aberg@stericsson.com> Signed-off-by: Linus Walleij <linus.walleij@stericsson.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/plat-nomadik/timer.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/arch/arm/plat-nomadik/timer.c b/arch/arm/plat-nomadik/timer.c
index d673888..aedf9c1 100644
--- a/arch/arm/plat-nomadik/timer.c
+++ b/arch/arm/plat-nomadik/timer.c
@@ -1,5 +1,5 @@
/*
- * linux/arch/arm/mach-nomadik/timer.c
+ * linux/arch/arm/plat-nomadik/timer.c
*
* Copyright (C) 2008 STMicroelectronics
* Copyright (C) 2010 Alessandro Rubini
@@ -75,7 +75,7 @@ static void nmdk_clkevt_mode(enum clock_event_mode mode,
cr = readl(mtu_base + MTU_CR(1));
writel(0, mtu_base + MTU_LR(1));
writel(cr | MTU_CRn_ENA, mtu_base + MTU_CR(1));
- writel(0x2, mtu_base + MTU_IMSC);
+ writel(1 << 1, mtu_base + MTU_IMSC);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
@@ -131,7 +131,7 @@ void __init nmdk_timer_init(void)
{
unsigned long rate;
struct clk *clk0;
- u32 cr;
+ u32 cr = MTU_CRn_32BITS;
clk0 = clk_get_sys("mtu0", NULL);
BUG_ON(IS_ERR(clk0));
@@ -139,12 +139,15 @@ void __init nmdk_timer_init(void)
clk_enable(clk0);
/*
- * Tick rate is 2.4MHz for Nomadik and 110MHz for ux500:
- * use a divide-by-16 counter if it's more than 16MHz
+ * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz
+ * for ux500.
+ * Use a divide-by-16 counter if the tick rate is more than 32MHz.
+ * At 32 MHz, the timer (with 32 bit counter) can be programmed
+ * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer
+ * with 16 gives too low timer resolution.
*/
- cr = MTU_CRn_32BITS;;
rate = clk_get_rate(clk0);
- if (rate > 16 << 20) {
+ if (rate > 32000000) {
rate /= 16;
cr |= MTU_CRn_PRESCALE_16;
} else {
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