diff mbox

OMAP3: PM: Dynamic calculation of SDRC clock stabilization delay

Message ID 5A47E75E594F054BAF48C5E4FC4B92AB030ADD4B50@dbde02.ent.ti.com (mailing list archive)
State Superseded
Delegated to: Kevin Hilman
Headers show

Commit Message

Reddy, Teerth Dec. 11, 2009, 12:05 p.m. UTC
None
diff mbox

Patch

diff --git a/arch/arm/mach-omap2/clock34xx.c b/arch/arm/mach-omap2/clock34xx.c
index da5bc1f..dd49938 100644
--- a/arch/arm/mach-omap2/clock34xx.c
+++ b/arch/arm/mach-omap2/clock34xx.c
@@ -37,6 +37,8 @@ 
 #include <asm/div64.h>
 #include <asm/clkdev.h>
 
+#include <plat/pmc.h>
+
 #include <plat/sdrc.h>
 #include "clock.h"
 #include "prm.h"
@@ -46,6 +48,8 @@ 
 
 static const struct clkops clkops_noncore_dpll_ops;
 
+unsigned int delay_sram;
+
 static void omap3430es2_clk_ssi_find_idlest(struct clk *clk,
 					    void __iomem **idlest_reg,
 					    u8 *idlest_bit);
@@ -333,14 +337,9 @@  static struct omap_clk omap34xx_clks[] = {
 /* Scale factor for fixed-point arith in omap3_core_dpll_m2_set_rate() */
 #define SDRC_MPURATE_SCALE		8
 
-/* 2^SDRC_MPURATE_BASE_SHIFT: MPU MHz that SDRC_MPURATE_LOOPS is defined for */
-#define SDRC_MPURATE_BASE_SHIFT		9
-
-/*
- * SDRC_MPURATE_LOOPS: Number of MPU loops to execute at
- * 2^MPURATE_BASE_SHIFT MHz for SDRC to stabilize
- */
-#define SDRC_MPURATE_LOOPS		96
+/* SDRC_TIME_STABILIZE: Time for SDRC to stabilize in us */
+/* hardcoded currently */
+#define	SDRC_TIME_STABILIZE		6
 
 /*
  * DPLL5_FREQ_FOR_USBHOST: USBHOST and USBTLL are the only clocks
@@ -870,16 +869,10 @@  static int omap3_core_dpll_m2_set_rate(struct clk *clk, unsigned long rate)
 		unlock_dll = 1;
 	}
 
-	/*
-	 * XXX This only needs to be done when the CPU frequency changes
-	 */
+	/* Calculate the number of MPU cycles to wait for SDRC to stabilize */
+
 	mpurate = arm_fck.rate / CYCLES_PER_MHZ;
-	c = (mpurate << SDRC_MPURATE_SCALE) >> SDRC_MPURATE_BASE_SHIFT;
-	c += 1;  /* for safety */
-	c *= SDRC_MPURATE_LOOPS;
-	c >>= SDRC_MPURATE_SCALE;
-	if (c == 0)
-		c = 1;
+	c = ((SDRC_TIME_STABILIZE * mpurate) / (delay_sram * 2));
 
 	pr_debug("clock: changing CORE DPLL rate from %lu to %lu\n", clk->rate,
 		 validrate);
@@ -1228,6 +1221,11 @@  int __init omap2_clk_init(void)
 	vclk = clk_get(NULL, "virt_prcm_set");
 	sclk = clk_get(NULL, "sys_ck");
 #endif
+
+	/* Measure sram delay */
+	delay_sram = measure_sram_delay(10000)/(10000*2);
+	pr_debug("SRAM delay: %d\n", delay_sram);
+
 	return 0;
 }
 
diff --git a/arch/arm/mach-omap2/sram34xx.S b/arch/arm/mach-omap2/sram34xx.S
index 82aa4a3..dc0ac72 100644
--- a/arch/arm/mach-omap2/sram34xx.S
+++ b/arch/arm/mach-omap2/sram34xx.S
@@ -298,3 +298,10 @@  core_m2_mask_val:
 ENTRY(omap3_sram_configure_core_dpll_sz)
 	.word	. - omap3_sram_configure_core_dpll
 
+ENTRY(__sram_wait_delay)
+	subs 	r0, r0, #1
+	bne	__sram_wait_delay
+	bx	lr
+
+ENTRY(__sram_wait_delay_sz)
+	.word	. - __sram_wait_delay
diff --git a/arch/arm/plat-omap/Makefile b/arch/arm/plat-omap/Makefile
index 95f8413..aac43da 100644
--- a/arch/arm/plat-omap/Makefile
+++ b/arch/arm/plat-omap/Makefile
@@ -15,6 +15,7 @@  obj-$(CONFIG_ARCH_OMAP16XX) += ocpi.o
 # omap_device support (OMAP2+ only at the moment)
 obj-$(CONFIG_ARCH_OMAP2) += omap_device.o
 obj-$(CONFIG_ARCH_OMAP3) += omap_device.o
+obj-$(CONFIG_ARCH_OMAP3) += pmc.o
 
 obj-$(CONFIG_OMAP_MCBSP) += mcbsp.o
 obj-$(CONFIG_OMAP_IOMMU) += iommu.o iovmm.o
diff --git a/arch/arm/plat-omap/include/plat/pmc.h b/arch/arm/plat-omap/include/plat/pmc.h
new file mode 100644
index 0000000..6d73782
--- /dev/null
+++ b/arch/arm/plat-omap/include/plat/pmc.h
@@ -0,0 +1,9 @@ 
+#ifndef __PMC_H__
+#define __PMC_H__
+extern void start_perf_counter(void);
+extern void start_cycle_counter(void);
+extern void stop_cycle_counter(void);
+extern void stop_perf_counter(void);
+extern unsigned int cycle_count(void);
+extern unsigned int delay_sram;
+#endif
diff --git a/arch/arm/plat-omap/include/plat/sram.h b/arch/arm/plat-omap/include/plat/sram.h
index 16a1b45..6019ed8 100644
--- a/arch/arm/plat-omap/include/plat/sram.h
+++ b/arch/arm/plat-omap/include/plat/sram.h
@@ -69,6 +69,12 @@  extern u32 omap3_sram_configure_core_dpll(
 			u32 sdrc_actim_ctrl_b_1, u32 sdrc_mr_1);
 extern unsigned long omap3_sram_configure_core_dpll_sz;
 
+extern unsigned int measure_sram_delay(unsigned int);
+
+extern u32 __sram_wait_delay(
+		unsigned int);
+extern unsigned long __sram_wait_delay_sz;
+
 #ifdef CONFIG_PM
 extern void omap_push_sram_idle(void);
 #else
diff --git a/arch/arm/plat-omap/pmc.c b/arch/arm/plat-omap/pmc.c
new file mode 100644
index 0000000..11acf42
--- /dev/null
+++ b/arch/arm/plat-omap/pmc.c
@@ -0,0 +1,47 @@ 
+#include <linux/module.h>
+
+void start_perf_counter(void)
+{
+	unsigned int r1 = 0;
+	asm("mrc p15, 0, %0, c9, c12, 0" : "=r" (r1));
+	r1 |= 0x1; /* enable counters */
+	asm("mcr p15, 0, %0, c9, c12, 0" : : "r" (r1));
+	return;
+}
+EXPORT_SYMBOL(start_perf_counter);
+
+void start_cycle_counter(void)
+{
+	unsigned int r2 = 0;
+	r2 = 0x80000000; /* enable cycle counter only */
+	asm("mcr p15, 0, %0, c9, c12, 1" : : "r" (r2));
+	return;
+}
+EXPORT_SYMBOL(start_cycle_counter);
+
+unsigned int cycle_count(void)
+{
+	unsigned int rd = 0;
+	asm("mrc p15, 0, %0, c9, c13, 0" : "=r" (rd));
+	return rd;
+}
+EXPORT_SYMBOL(cycle_count);
+
+
+void stop_cycle_counter(void)
+{
+	unsigned int r3 = 0;
+	r3 = 0x0; /* disable cycle counter */
+	asm("mcr p15, 0, %0, c9, c12, 1" : : "r" (r3));
+	return;
+}
+EXPORT_SYMBOL(stop_cycle_counter);
+
+void stop_perf_counter(void)
+{
+	unsigned int r1 = 0;
+	r1 = 0x0; /* disable counters */
+	asm("mcr p15, 0, %0, c9, c12, 0" : : "r" (r1));
+	return;
+}
+EXPORT_SYMBOL(stop_perf_counter);
diff --git a/arch/arm/plat-omap/sram.c b/arch/arm/plat-omap/sram.c
index 3e92366..4ed6a48 100644
--- a/arch/arm/plat-omap/sram.c
+++ b/arch/arm/plat-omap/sram.c
@@ -29,6 +29,10 @@ 
 #include <plat/board.h>
 #include <plat/cpu.h>
 
+#ifdef CONFIG_ARCH_OMAP3
+#include <plat/pmc.h>
+#endif
+
 #include <plat/control.h>
 
 #if defined(CONFIG_ARCH_OMAP2) || defined(CONFIG_ARCH_OMAP3)
@@ -423,6 +427,25 @@  static inline int omap34xx_sram_init(void)
 }
 #endif
 
+
+#ifdef CONFIG_ARCH_OMAP3
+unsigned int measure_sram_delay(unsigned int loop)
+{
+	unsigned int start = 0, end = 0;
+	void (*_omap3_sram_delay)(unsigned long);
+	_omap3_sram_delay = omap_sram_push(__sram_wait_delay,
+						__sram_wait_delay_sz);
+	start_perf_counter();
+	start_cycle_counter();
+	start = cycle_count();
+	_omap3_sram_delay(loop);
+	end = cycle_count();
+	stop_cycle_counter();
+	stop_perf_counter();
+	return end - start;
+}
+#endif
+
 int __init omap_sram_init(void)
 {
 	omap_detect_sram();