[PATCH-V4 3/3] ARM: OMAP: Make OMAP clocksource source selection using kernel param
Vaibhav Hiremath
hvaibhav at ti.com
Tue Apr 24 05:45:49 EDT 2012
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
So ideally we can kill the gptimer based clocksource option but there
are some OMAP based derivative SoCs like AM33XX which doesn't have
32K sync-timer hardware IP and need to fallback on 32KHz based gptimer
clocksource.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
Also, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Signed-off-by: Vaibhav Hiremath <hvaibhav at ti.com>
Signed-off-by: Felipe Balbi <balbi at ti.com>
Cc: Santosh Shilimkar <santosh.shilimkar at ti.com>
Cc: Kevin Hilman <khilman at ti.com>
Cc: Benoit Cousson <b-cousson at ti.com>
Cc: Tony Lindgren <tony at atomide.com>
Cc: Paul Walmsley <paul at pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti at ti.com>
Cc: Ming Lei <tom.leiming at gmail.com>
---
arch/arm/mach-omap1/timer32k.c | 6 ++-
arch/arm/mach-omap2/timer.c | 99 +++++++++++++++++++++------
arch/arm/plat-omap/counter_32k.c | 108 +++++++++++++++---------------
arch/arm/plat-omap/include/plat/common.h | 2 +-
4 files changed, 138 insertions(+), 77 deletions(-)
diff --git a/arch/arm/mach-omap1/timer32k.c b/arch/arm/mach-omap1/timer32k.c
index 325b9a0..6262e11 100644
--- a/arch/arm/mach-omap1/timer32k.c
+++ b/arch/arm/mach-omap1/timer32k.c
@@ -71,6 +71,7 @@
/* 16xx specific defines */
#define OMAP1_32K_TIMER_BASE 0xfffb9000
+#define OMAP1_32KSYNC_TIMER_BASE 0xfffbc400
#define OMAP1_32K_TIMER_CR 0x08
#define OMAP1_32K_TIMER_TVR 0x00
#define OMAP1_32K_TIMER_TCR 0x04
@@ -184,7 +185,10 @@ static __init void omap_init_32k_timer(void)
*/
bool __init omap_32k_timer_init(void)
{
- omap_init_clocksource_32k();
+ u32 pbase;
+
+ pbase = cpu_is_omap16xx() ? OMAP1_32KSYNC_TIMER_BASE : NULL;
+ omap_init_clocksource_32k(pbase, SZ_1K);
omap_init_32k_timer();
return true;
diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
index ecec873..2afc4ab 100644
--- a/arch/arm/mach-omap2/timer.c
+++ b/arch/arm/mach-omap2/timer.c
@@ -243,22 +243,8 @@ static void __init omap2_gp_clockevent_init(int gptimer_id,
}
/* Clocksource code */
-
-#ifdef CONFIG_OMAP_32K_TIMER
-/*
- * When 32k-timer is enabled, don't use GPTimer for clocksource
- * instead, just leave default clocksource which uses the 32k
- * sync counter. See clocksource setup in plat-omap/counter_32k.c
- */
-
-static void __init omap2_gp_clocksource_init(int unused, const char *dummy)
-{
- omap_init_clocksource_32k();
-}
-
-#else
-
static struct omap_dm_timer clksrc;
+static bool use_gptimer_clksrc;
/*
* clocksource
@@ -285,7 +271,33 @@ static u32 notrace dmtimer_read_sched_clock(void)
}
/* Setup free-running counter for clocksource */
-static void __init omap2_gp_clocksource_init(int gptimer_id,
+static int __init omap2_sync32k_clocksource_init(void)
+{
+ int ret;
+ struct omap_hwmod *oh;
+ struct resource res;
+ const char *oh_name = "counter_32k";
+
+ oh = omap_hwmod_lookup(oh_name);
+ if (!oh || oh->slaves_cnt == 0)
+ return -ENODEV;
+
+ ret = omap_hwmod_get_resource_byname(oh, IORESOURCE_MEM, NULL, &res);
+ if (ret) {
+ pr_warn("%s: failed to get counter_32k resource (%d)\n",
+ __func__, ret);
+ return ret;
+ }
+
+ ret = omap_init_clocksource_32k(res.start, resource_size(&res));
+ if (ret)
+ pr_warn("%s: failed to initialize counter_32k (%d)\n",
+ __func__, ret);
+
+ return ret;
+}
+
+static void __init omap2_gptimer_clocksource_init(int gptimer_id,
const char *fck_source)
{
int res;
@@ -293,9 +305,6 @@ static void __init omap2_gp_clocksource_init(int gptimer_id,
res = omap_dm_timer_init_one(&clksrc, gptimer_id, fck_source);
BUG_ON(res);
- pr_info("OMAP clocksource: GPTIMER%d at %lu Hz\n",
- gptimer_id, clksrc.rate);
-
__omap_dm_timer_load_start(&clksrc,
OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0, 1);
setup_sched_clock(dmtimer_read_sched_clock, 32, clksrc.rate);
@@ -303,15 +312,36 @@ static void __init omap2_gp_clocksource_init(int gptimer_id,
if (clocksource_register_hz(&clocksource_gpt, clksrc.rate))
pr_err("Could not register clocksource %s\n",
clocksource_gpt.name);
+ else
+ pr_info("OMAP clocksource: GPTIMER%d at %lu Hz\n",
+ gptimer_id, clksrc.rate);
+}
+
+static void __init omap2_clocksource_init(int gptimer_id,
+ const char *fck_source)
+{
+ /*
+ * First give preference to kernel parameter configuration
+ * by user (clocksource="gp timer").
+ *
+ * In case of missing kernel parameter for clocksource,
+ * first check for availability for 32k-sync timer, in case
+ * of failure in finding 32k_counter module or registering
+ * it as clocksource, execution will fallback to gp-timer.
+ */
+ if (use_gptimer_clksrc == true)
+ omap2_gptimer_clocksource_init(gptimer_id, fck_source);
+ else if (omap2_sync32k_clocksource_init())
+ /* Fall back to gp-timer code */
+ omap2_gptimer_clocksource_init(gptimer_id, fck_source);
}
-#endif
#define OMAP_SYS_TIMER_INIT(name, clkev_nr, clkev_src, \
clksrc_nr, clksrc_src) \
static void __init omap##name##_timer_init(void) \
{ \
omap2_gp_clockevent_init((clkev_nr), clkev_src); \
- omap2_gp_clocksource_init((clksrc_nr), clksrc_src); \
+ omap2_clocksource_init((clksrc_nr), clksrc_src); \
}
#define OMAP_SYS_TIMER(name) \
@@ -342,7 +372,7 @@ static DEFINE_TWD_LOCAL_TIMER(twd_local_timer,
static void __init omap4_timer_init(void)
{
omap2_gp_clockevent_init(1, OMAP4_CLKEV_SOURCE);
- omap2_gp_clocksource_init(2, OMAP4_MPU_SOURCE);
+ omap2_clocksource_init(2, OMAP4_MPU_SOURCE);
#ifdef CONFIG_LOCAL_TIMERS
/* Local timers are not supprted on OMAP4430 ES1.0 */
if (omap_rev() != OMAP4430_REV_ES1_0) {
@@ -510,3 +540,28 @@ static int __init omap2_dm_timer_init(void)
return 0;
}
arch_initcall(omap2_dm_timer_init);
+
+/**
+ * omap2_override_clocksource - clocksource override with user configuration
+ *
+ * Allows user to override default clocksource, using kernel parameter
+ * clocksource="gp timer"
+ *
+ * Note that, here we are using same standard kernel parameter "clocksource=",
+ * and not introducing any OMAP specific interface.
+ */
+static int __init omap2_override_clocksource(char *str)
+{
+ if (!str)
+ return 0;
+ /*
+ * For OMAP architecture, we only have two options
+ * - sync_32k (default)
+ * - gp timer
+ */
+ if (!strcmp(str, "gp timer"))
+ use_gptimer_clksrc = true;
+
+ return 0;
+}
+early_param("clocksource", omap2_override_clocksource);
diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
index 5068fe5..3e3cdab 100644
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -27,19 +27,20 @@
#include <plat/clock.h>
+/* OMAP2_32KSYNCNT_CR_OFF: offset of 32ksync counter register */
+#define OMAP2_32KSYNCNT_CR_OFF 0x10
+
/*
* 32KHz clocksource ... always available, on pretty most chips except
* OMAP 730 and 1510. Other timers could be used as clocksources, with
* higher resolution in free-running counter modes (e.g. 12 MHz xtal),
* but systems won't necessarily want to spend resources that way.
*/
-static void __iomem *timer_32k_base;
-
-#define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410
+static void __iomem *sync32k_cnt_reg;
static u32 notrace omap_32k_read_sched_clock(void)
{
- return timer_32k_base ? __raw_readl(timer_32k_base) : 0;
+ return sync32k_cnt_reg ? __raw_readl(sync32k_cnt_reg) : 0;
}
/**
@@ -59,7 +60,7 @@ void read_persistent_clock(struct timespec *ts)
struct timespec *tsp = &persistent_ts;
last_cycles = cycles;
- cycles = timer_32k_base ? __raw_readl(timer_32k_base) : 0;
+ cycles = sync32k_cnt_reg ? __raw_readl(sync32k_cnt_reg) : 0;
delta = cycles - last_cycles;
nsecs = clocksource_cyc2ns(delta, persistent_mult, persistent_shift);
@@ -68,54 +69,55 @@ void read_persistent_clock(struct timespec *ts)
*ts = *tsp;
}
-int __init omap_init_clocksource_32k(void)
+/**
+ * omap_init_clocksource_32k - setup and register counter 32k as a
+ * kernel clocksource
+ * @pbase: base addr of counter_32k module
+ * @size: size of counter_32k to map
+ *
+ * Returns 0 upon success or negative error code upon failure.
+ *
+ */
+int __init omap_init_clocksource_32k(u32 pbase, unsigned long size)
{
- static char err[] __initdata = KERN_ERR
- "%s: can't register clocksource!\n";
-
- if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
- u32 pbase;
- unsigned long size = SZ_4K;
- void __iomem *base;
- struct clk *sync_32k_ick;
-
- if (cpu_is_omap16xx()) {
- pbase = OMAP16XX_TIMER_32K_SYNCHRONIZED;
- size = SZ_1K;
- } else if (cpu_is_omap2420())
- pbase = OMAP2420_32KSYNCT_BASE + 0x10;
- else if (cpu_is_omap2430())
- pbase = OMAP2430_32KSYNCT_BASE + 0x10;
- else if (cpu_is_omap34xx())
- pbase = OMAP3430_32KSYNCT_BASE + 0x10;
- else if (cpu_is_omap44xx())
- pbase = OMAP4430_32KSYNCT_BASE + 0x10;
- else
- return -ENODEV;
-
- /* For this to work we must have a static mapping in io.c for this area */
- base = ioremap(pbase, size);
- if (!base)
- return -ENODEV;
-
- sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
- if (!IS_ERR(sync_32k_ick))
- clk_enable(sync_32k_ick);
-
- timer_32k_base = base;
-
- /*
- * 120000 rough estimate from the calculations in
- * __clocksource_updatefreq_scale.
- */
- clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
- 32768, NSEC_PER_SEC, 120000);
-
- if (clocksource_mmio_init(base, "32k_counter", 32768, 250, 32,
- clocksource_mmio_readl_up))
- printk(err, "32k_counter");
-
- setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
+ int ret;
+ void __iomem *base;
+ struct clk *sync32k_ick;
+
+ if (!pbase || !size)
+ return -ENODEV;
+ /*
+ * For this to work we must have a static mapping in io.c
+ * for this area
+ */
+ base = ioremap(pbase, size);
+ if (!base) {
+ pr_err("32k_counter: failed to map base addr\n");
+ return -ENODEV;
}
- return 0;
+
+ sync32k_ick = clk_get(NULL, "omap_32ksync_ick");
+ if (!IS_ERR(sync32k_ick))
+ clk_enable(sync32k_ick);
+
+ sync32k_cnt_reg = base + OMAP2_32KSYNCNT_CR_OFF;
+
+ /*
+ * 120000 rough estimate from the calculations in
+ * __clocksource_updatefreq_scale.
+ */
+ clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
+ 32768, NSEC_PER_SEC, 120000);
+
+ ret = clocksource_mmio_init(base, "32k_counter", 32768, 250, 32,
+ clocksource_mmio_readl_up);
+ if (ret) {
+ pr_err("32k_counter: can't register clocksource\n");
+ return ret;
+ }
+
+ setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
+ pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
+
+ return ret;
}
diff --git a/arch/arm/plat-omap/include/plat/common.h b/arch/arm/plat-omap/include/plat/common.h
index a557b84..eed5335 100644
--- a/arch/arm/plat-omap/include/plat/common.h
+++ b/arch/arm/plat-omap/include/plat/common.h
@@ -30,7 +30,7 @@
#include <plat/i2c.h>
#include <plat/omap_hwmod.h>
-extern int __init omap_init_clocksource_32k(void);
+extern int __init omap_init_clocksource_32k(u32 pbase, unsigned long size);
extern void __init omap_check_revision(void);
--
1.7.0.4
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