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Thu, 11 Mar 2010 16:58:41 +0530 (IST) From: Pramod Gurav To: linux-omap@vger.kernel.org Cc: Teerth Reddy , Romit Dasgupta , Pramod Gurav , Vishwanath Sripathy Subject: [PATCH v3 1/2] OMAP3: SDRC: Dynamic Calculation of SDRC stall latency during DVFS Date: Thu, 11 Mar 2010 17:04:56 +0530 Message-Id: <1268307297-23330-2-git-send-email-pramod.gurav@ti.com> X-Mailer: git-send-email 1.5.6.3 In-Reply-To: <1268307297-23330-1-git-send-email-pramod.gurav@ti.com> References: <1268307297-23330-1-git-send-email-pramod.gurav@ti.com> Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Thu, 11 Mar 2010 11:28:48 +0000 (UTC) diff --git a/arch/arm/mach-omap2/clkt34xx_dpll3m2.c b/arch/arm/mach-omap2/clkt34xx_dpll3m2.c index b2b1e37..3f61eb2 100644 --- a/arch/arm/mach-omap2/clkt34xx_dpll3m2.c +++ b/arch/arm/mach-omap2/clkt34xx_dpll3m2.c @@ -24,6 +24,7 @@ #include #include #include +#include #include "clock.h" #include "clock3xxx.h" @@ -32,6 +33,13 @@ #define CYCLES_PER_MHZ 1000000 +#define DPLL_M_MASK 0x7ff +#define DPLL_N_MASK 0x7f +#define DPLL_M2_MASK 0x1f +#define SHIFT_DPLL_M 16 +#define SHIFT_DPLL_N 8 +#define SHIFT_DPLL_M2 27 + /* * CORE DPLL (DPLL3) M2 divider rate programming functions * @@ -56,6 +64,11 @@ int omap3_core_dpll_m2_set_rate(struct clk *clk, unsigned long rate) struct omap_sdrc_params *sdrc_cs0; struct omap_sdrc_params *sdrc_cs1; int ret; + u32 clk_sel_regval; + u32 core_dpll_mul_m, core_dpll_div_n, core_dpll_clkoutdiv_m2; + u32 sys_clk_rate, sdrc_clk_stab; + u32 refclk, clkoutx2, switch_latency; + unsigned int delay_sram; if (!clk || !rate) return -EINVAL; @@ -79,16 +92,41 @@ int omap3_core_dpll_m2_set_rate(struct clk *clk, unsigned long rate) unlock_dll = 1; } + clk_sel_regval = __raw_readl(clk->clksel_reg); + + /* Get the M, N and M2 values required for getting sdrc clk stab */ + core_dpll_mul_m = (clk_sel_regval >> SHIFT_DPLL_M) & DPLL_M_MASK; + core_dpll_div_n = (clk_sel_regval >> SHIFT_DPLL_N) & DPLL_N_MASK; + core_dpll_clkoutdiv_m2 = (clk_sel_regval >> SHIFT_DPLL_M2) & + DPLL_M2_MASK; + sys_clk_rate = clk_get_rate(clk_get(NULL, "sys_ck")); + + sys_clk_rate = sys_clk_rate / CYCLES_PER_MHZ; + + /* wait time for L3 clk stabilization = 4*REFCLK + 8*CLKOUTX2 */ + refclk = (4 * (core_dpll_div_n + 1)) / sys_clk_rate; + clkoutx2 = ((core_dpll_div_n + 1) * core_dpll_clkoutdiv_m2) / + (sys_clk_rate * core_dpll_mul_m * 2); + switch_latency = refclk + 8 * clkoutx2; + + /* Adding 2us to sdrc clk stab */ + sdrc_clk_stab = switch_latency + 2; + + delay_sram = delay_sram_val(); + /* - * 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_clk_stab * _mpurate) / (delay_sram * 2)); + + pr_debug("m = %d, n = %d, m2 =%d\n", core_dpll_mul_m, core_dpll_div_n, + core_dpll_clkoutdiv_m2); + pr_debug("switch_latency = %d, sys_clk_rate = %d, cycles = %d\n", + switch_latency, sys_clk_rate, c); 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 628e8de..a9f2204 100644 --- a/arch/arm/mach-omap2/clock34xx.h +++ b/arch/arm/mach-omap2/clock34xx.h @@ -12,4 +12,6 @@ extern const struct clkops clkops_omap3430es2_ssi_wait; extern const struct clkops clkops_omap3430es2_hsotgusb_wait; extern const struct clkops clkops_omap3430es2_dss_usbhost_wait; +unsigned int delay_sram_val(void); + #endif diff --git a/arch/arm/mach-omap2/clock3xxx_data.c b/arch/arm/mach-omap2/clock3xxx_data.c index 57522de..9726f4b 100644 --- a/arch/arm/mach-omap2/clock3xxx_data.c +++ b/arch/arm/mach-omap2/clock3xxx_data.c @@ -22,6 +22,7 @@ #include #include +#include #include "clock.h" #include "clock3xxx.h" @@ -57,6 +58,8 @@ static struct clk dpll1_fck; static struct clk dpll2_fck; +unsigned int delay_sram; + /* PRM CLOCKS */ /* According to timer32k.c, this is a 32768Hz clock, not a 32000Hz clock. */ @@ -3599,5 +3602,14 @@ int __init omap3xxx_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; } + +unsigned int delay_sram_val(void) +{ + return delay_sram; +} diff --git a/arch/arm/mach-omap2/sram34xx.S b/arch/arm/mach-omap2/sram34xx.S index de99ba2..00da20a 100644 --- a/arch/arm/mach-omap2/sram34xx.S +++ b/arch/arm/mach-omap2/sram34xx.S @@ -313,3 +313,14 @@ core_m2_mask_val: ENTRY(omap3_sram_configure_core_dpll_sz) .word . - omap3_sram_configure_core_dpll +ENTRY(__sram_wait_delay) + stmfd sp!, {lr} @ store return addr to stack + + loop1: + subs r0, r0, #1 @ loop till counter = 0 + bne loop1 + + ldmfd sp!, {pc} @ restore return address + +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..dd294a8 100644 --- a/arch/arm/plat-omap/include/plat/sram.h +++ b/arch/arm/plat-omap/include/plat/sram.h @@ -69,6 +69,10 @@ 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 void __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 51f4dfb..82d8df0 100644 --- a/arch/arm/plat-omap/sram.c +++ b/arch/arm/plat-omap/sram.c @@ -30,6 +30,9 @@ #include #include +#include +#include +#include #include #if defined(CONFIG_ARCH_OMAP2) || defined(CONFIG_ARCH_OMAP3) @@ -437,11 +440,57 @@ static inline int omap34xx_sram_init(void) } #endif +#ifdef CONFIG_ARCH_OMAP3 +void (*_omap3_sram_delay)(unsigned int); +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; + unsigned int start = 0, end = 0; + + omap_dm_timer_init(); + gpt = omap_dm_timer_request(); + if (!gpt) { + pr_err("Could not get the gptimer\n"); + return -1; + } + + 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); + start = omap_dm_timer_read_counter(gpt); + _omap3_sram_delay(loop); + end = omap_dm_timer_read_counter(gpt); + diff = end - start; + 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())