diff mbox

ARM : OMAP3 : Dynamic calculation of SDRC clock stabilization delay

Message ID 5A47E75E594F054BAF48C5E4FC4B92AB031E0A30BD@dbde02.ent.ti.com (mailing list archive)
State Changes Requested
Delegated to: Paul Walmsley
Headers show

Commit Message

Reddy, Teerth Jan. 5, 2010, 6:19 a.m. UTC
None
diff mbox

Patch

diff --git a/arch/arm/mach-omap2/clock34xx.c b/arch/arm/mach-omap2/clock34xx.c
index d4217b9..da3d26e 100644
--- a/arch/arm/mach-omap2/clock34xx.c
+++ b/arch/arm/mach-omap2/clock34xx.c
@@ -51,9 +51,18 @@ 
  */
 #define DPLL5_FREQ_FOR_USBHOST		120000000
 
+/*
+ * SDRC_TIME_STABILIZE: Time for SDRC to stabilize in us
+ * TO DO: Use formula to calculate across all platforms
+ */
+#define		SDRC_TIME_STABILIZE	6
+
 /* needed by omap3_core_dpll_m2_set_rate() */
 struct clk *sdrc_ick_p, *arm_fck_p;
 
+/* SRAM delay required for sdrc clk stab delay calculation */
+unsigned int delay_sram;
+
 /**
  * omap3430es2_clk_ssi_find_idlest - return CM_IDLEST info for SSI
  * @clk: struct clk * being enabled
@@ -210,16 +219,10 @@  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_p->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);
diff --git a/arch/arm/mach-omap2/clock34xx.h b/arch/arm/mach-omap2/clock34xx.h
index 9a2c07e..1bc5044 100644
--- a/arch/arm/mach-omap2/clock34xx.h
+++ b/arch/arm/mach-omap2/clock34xx.h
@@ -21,4 +21,6 @@  extern const struct clkops clkops_omap3430es2_hsotgusb_wait;
 extern const struct clkops clkops_omap3430es2_dss_usbhost_wait;
 extern const struct clkops clkops_noncore_dpll_ops;
 
+extern unsigned int delay_sram;
+
 #endif
diff --git a/arch/arm/mach-omap2/clock34xx_data.c b/arch/arm/mach-omap2/clock34xx_data.c
index c6031d7..a721585 100644
--- a/arch/arm/mach-omap2/clock34xx_data.c
+++ b/arch/arm/mach-omap2/clock34xx_data.c
@@ -22,6 +22,7 @@ 
 
 #include <plat/control.h>
 #include <plat/clkdev_omap.h>
+#include <plat/sram.h>
 
 #include "clock.h"
 #include "clock34xx.h"
@@ -3289,5 +3290,8 @@  int __init omap2_clk_init(void)
 	sdrc_ick_p = clk_get(NULL, "sdrc_ick");
 	arm_fck_p = clk_get(NULL, "arm_fck");
 
+	/* Measure sram delay */
+	delay_sram = measure_sram_delay(10000);
+	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 de99ba2..b4fba50 100644
--- a/arch/arm/mach-omap2/sram34xx.S
+++ b/arch/arm/mach-omap2/sram34xx.S
@@ -68,6 +68,10 @@ 
 /* CM_CLKSEL1_PLL bit settings */
 #define CORE_DPLL_CLKOUT_DIV_SHIFT	0x1b
 
+#define	GPTIMER10_TCRR_PHY			0x48086028
+
+#define	GPTIMER10_TCRR	OMAP2_L4_IO_ADDRESS(GPTIMER10_TCRR_PHY)
+
 /*
  * omap3_sram_configure_core_dpll - change DPLL3 M2 divider
  *
@@ -313,3 +317,24 @@  core_m2_mask_val:
 ENTRY(omap3_sram_configure_core_dpll_sz)
 	.word	. - omap3_sram_configure_core_dpll
 
+ENTRY(__sram_wait_delay)
+	stmfd	sp!, {r1-r12, lr}	@ store regs to stack
+ 	ldr	r2, gptimer10_counter
+	ldr	r3, [r2]
+
+loop1:
+	subs 	r0, r0, #1
+	bne	loop1
+
+	isb
+	ldr	r4, [r2]
+	subs	r5, r4, r3
+
+	mov 	r0, r5 			@ return value
+	ldmfd	sp!, {r1-r12, pc}	@ restore regs and return
+
+gptimer10_counter:
+	.word	GPTIMER10_TCRR
+
+ENTRY(__sram_wait_delay_sz)
+	.word	. - __sram_wait_delay
diff --git a/arch/arm/plat-omap/include/plat/sram.h b/arch/arm/plat-omap/include/plat/sram.h
index 16a1b45..7d0be2a 100644
--- a/arch/arm/plat-omap/include/plat/sram.h
+++ b/arch/arm/plat-omap/include/plat/sram.h
@@ -69,6 +69,11 @@  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/sram.c b/arch/arm/plat-omap/sram.c
index d8d5094..6e0e550 100644
--- a/arch/arm/plat-omap/sram.c
+++ b/arch/arm/plat-omap/sram.c
@@ -30,6 +30,9 @@ 
 #include <plat/cpu.h>
 #include <plat/vram.h>
 
+#include <linux/clk.h>
+#include <plat/dmtimer.h>
+
 #include <plat/control.h>
 
 #if defined(CONFIG_ARCH_OMAP2) || defined(CONFIG_ARCH_OMAP3)
@@ -437,11 +440,51 @@  static inline int omap34xx_sram_init(void)
 }
 #endif
 
+
+#ifdef CONFIG_ARCH_OMAP3
+unsigned long (*_omap3_sram_delay)(unsigned long);
+unsigned int  measure_sram_delay(unsigned int loop)
+{
+	static struct omap_dm_timer *gpt;
+	unsigned long flags, diff = 0, gt_rate, mpurate;
+	unsigned int delay_sram, error_gain;
+
+	omap_dm_timer_init();
+	gpt = omap_dm_timer_request_specific(10);
+	if (!gpt)
+		pr_err("Could not get the gptimer\n");
+	omap_dm_timer_set_source(gpt, OMAP_TIMER_SRC_SYS_CLK);
+
+	gt_rate = clk_get_rate(omap_dm_timer_get_fclk(gpt));
+	omap_dm_timer_set_load_start(gpt, 0, 0);
+
+	local_irq_save(flags);
+	diff = _omap3_sram_delay(loop);
+	local_irq_restore(flags);
+
+	omap_dm_timer_stop(gpt);
+	omap_dm_timer_free(gpt);
+
+	mpurate = clk_get_rate(clk_get(NULL, "arm_fck"));
+
+	/* calculate the sram delay */
+	delay_sram = (((mpurate / gt_rate) * diff) / (loop * 2));
+
+	error_gain = mpurate / gt_rate;
+	delay_sram = delay_sram + error_gain;
+
+	return delay_sram;
+}
+#endif
+
 int __init omap_sram_init(void)
 {
 	omap_detect_sram();
 	omap_map_sram();
 
+	_omap3_sram_delay = omap_sram_push(__sram_wait_delay,
+						__sram_wait_delay_sz);
+
 	if (!(cpu_class_is_omap2()))
 		omap1_sram_init();
 	else if (cpu_is_omap242x())