arm: tegra: clock: Reading APB bus before disabling clock

It may be possible that write operation on apb bus does not get
complete before disabling clock if the clock is disabled just after
the write on apb bus.
To have proper sequence of operation, it is require to read back the
apb bus to make sure the write operation is completed.

bug 833341

This is cherry pick of change http://git-master/r/#change,32556
in main but hand-merged.

Change-Id: I1d73a2fdfb35450220f53973d56984c9b89fdd27
Reviewed-on: http://git-master/r/45985
Reviewed-by: Alok Chauhan <alokc@nvidia.com>
Tested-by: Alok Chauhan <alokc@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
Reviewed-by: Mayuresh Kulkarni <mkulkarni@nvidia.com>

2 files changed, 52 insertions, 31 deletions

diff --git a/arch/arm/mach-tegra/clock.h b/arch/arm/mach-tegra/clock.h
index acbabaa94b60..01cb68dfa407 100644
--- a/arch/arm/mach-tegra/clock.h
+++ b/arch/arm/mach-tegra/clock.h
@@ -41,6 +41,7 @@
 #define PLL_ALT_MISC_REG	(1 << 13)
 #define PLLU			(1 << 14)
 #define ENABLE_ON_INIT		(1 << 28)
+#define PERIPH_ON_APB		(1 << 29)
 
 #define MAX_SAME_LIMIT_SKU_IDS	16
 
diff --git a/arch/arm/mach-tegra/tegra2_clocks.c b/arch/arm/mach-tegra/tegra2_clocks.c
index 15f3b75cbdee..4f58d8276fa7 100644
--- a/arch/arm/mach-tegra/tegra2_clocks.c
+++ b/arch/arm/mach-tegra/tegra2_clocks.c
@@ -155,8 +155,10 @@
 
 static void __iomem *reg_clk_base = IO_ADDRESS(TEGRA_CLK_RESET_BASE);
 static void __iomem *reg_pmc_base = IO_ADDRESS(TEGRA_PMC_BASE);
+static void __iomem *misc_gp_hidrev_base = IO_ADDRESS(TEGRA_APB_MISC_BASE);
 
 static void tegra2_clk_shared_bus_update(struct clk *bus);
+#define MISC_GP_HIDREV			0x804
 
 /*
  * Some peripheral clocks share an enable bit, so refcount the enable bits
@@ -172,6 +174,8 @@ static int tegra_periph_clk_enable_refcount[3 * 32];
 	__raw_writel(value, (u32)reg_pmc_base + (reg))
 #define pmc_readl(reg) \
 	__raw_readl((u32)reg_pmc_base + (reg))
+#define chipid_readl() \
+	__raw_readl((u32)misc_gp_hidrev_base + MISC_GP_HIDREV)
 
 unsigned long clk_measure_input_freq(void)
 {
@@ -968,25 +972,41 @@ static int tegra2_periph_clk_enable(struct clk *c)
 
 static void tegra2_periph_clk_disable(struct clk *c)
 {
+	unsigned long val;
 	pr_debug("%s on clock %s\n", __func__, c->name);
 
 	if (c->refcnt)
 		tegra_periph_clk_enable_refcount[c->u.periph.clk_num]--;
 
-	if (tegra_periph_clk_enable_refcount[c->u.periph.clk_num] == 0)
+	if (tegra_periph_clk_enable_refcount[c->u.periph.clk_num] == 0) {
+		/* If peripheral is in the APB bus then read the APB bus to
+		 * flush the write operation in apb bus. This will avoid the
+		 * peripheral access after disabling clock*/
+		if (c->flags & PERIPH_ON_APB)
+			val = chipid_readl();
+
 		clk_writel(PERIPH_CLK_TO_ENB_BIT(c),
 			CLK_OUT_ENB_CLR + PERIPH_CLK_TO_ENB_SET_REG(c));
+	}
 }
 
 static void tegra2_periph_clk_reset(struct clk *c, bool assert)
 {
 	unsigned long base = assert ? RST_DEVICES_SET : RST_DEVICES_CLR;
+	unsigned long val;
 
 	pr_debug("%s %s on clock %s\n", __func__,
 		 assert ? "assert" : "deassert", c->name);
-	if (!(c->flags & PERIPH_NO_RESET))
+	if (!(c->flags & PERIPH_NO_RESET)) {
+		/* If peripheral is in the APB bus then read the APB bus to
+		 * flush the write operation in apb bus. This will avoid the
+		 * peripheral access after disabling clock*/
+		if (c->flags & PERIPH_ON_APB)
+			val = chipid_readl();
+
 		clk_writel(PERIPH_CLK_TO_ENB_BIT(c),
 			   base + PERIPH_CLK_TO_ENB_SET_REG(c));
+	}
 }
 
 static int tegra2_periph_clk_set_parent(struct clk *c, struct clk *p)
@@ -2126,27 +2146,27 @@ static struct clk tegra_clk_emc = {
 	}
 
 struct clk tegra_list_periph_clks[] = {
-	PERIPH_CLK("rtc",	"rtc-tegra",		NULL,	4,	0,	0x31E,	32768,     mux_clk_32k,			PERIPH_NO_RESET),
-	PERIPH_CLK("kbc",	"tegra-kbc",		NULL,	36, 	0,	0x31E,	32768,	   mux_clk_32k, PERIPH_NO_RESET),
+	PERIPH_CLK("rtc",	"rtc-tegra",		NULL,	4,	0,	0x31E,	32768,     mux_clk_32k,			PERIPH_NO_RESET | PERIPH_ON_APB),
+	PERIPH_CLK("kbc",	"tegra-kbc",		NULL,	36, 	0,	0x31E,	32768,	   mux_clk_32k, PERIPH_NO_RESET | PERIPH_ON_APB),
 	PERIPH_CLK("timer",	"timer",		NULL,	5,	0,	0x31E,	26000000,  mux_clk_m,			0),
 	PERIPH_CLK("kfuse",	"kfuse-tegra",		NULL,	40,	0,	0x31E,  26000000,  mux_clk_m,			0),
 	PERIPH_CLK("fuse",	"fuse-tegra",		"fuse",	39,	0,	0x31E,  26000000,  mux_clk_m,			0),
 	PERIPH_CLK("fuse_burn",	"fuse-tegra",		"fuse_burn",	39,	0,	0x31E,  26000000,  mux_clk_m,		0),
-	PERIPH_CLK("i2s1",	"i2s.0",		NULL,	11,	0x100,	0x31E,	26000000,  mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("i2s2",	"i2s.1",		NULL,	18,	0x104,	0x31E,	26000000,  mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("spdif_out",	"spdif_out",		NULL,	10,	0x108,	0x31E,	100000000, mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("spdif_in",	"spdif_in",		NULL,	10,	0x10c,	0x31E,	100000000, mux_pllp_pllc_pllm,		MUX | DIV_U71),
-	PERIPH_CLK("pwm",	"pwm",			NULL,	17,	0x110,	0x71C,	432000000, mux_pllp_pllc_audio_clkm_clk32,	MUX | DIV_U71),
-	PERIPH_CLK("spi",	"spi",			NULL,	43,	0x114,	0x31E,	40000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
+	PERIPH_CLK("i2s1",	"i2s.0",		NULL,	11,	0x100,	0x31E,	26000000,  mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("i2s2",	"i2s.1",		NULL,	18,	0x104,	0x31E,	26000000,  mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("spdif_out",	"spdif_out",		NULL,	10,	0x108,	0x31E,	100000000, mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("spdif_in",	"spdif_in",		NULL,	10,	0x10c,	0x31E,	100000000, mux_pllp_pllc_pllm,		MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("pwm",	"pwm",			NULL,	17,	0x110,	0x71C,	432000000, mux_pllp_pllc_audio_clkm_clk32,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("spi",	"spi",			NULL,	43,	0x114,	0x31E,	40000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("xio",	"xio",			NULL,	45,	0x120,	0x31E,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("twc",	"twc",			NULL,	16,	0x12c,	0x31E,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc1",	"spi_tegra.0",		NULL,	41,	0x134,	0x31E,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc2",	"spi_tegra.1",		NULL,	44,	0x118,	0x31E,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc3",	"spi_tegra.2",		NULL,	46,	0x11c,	0x31E,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc4",	"spi_tegra.3",		NULL,	68,	0x1b4,	0x31E,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
+	PERIPH_CLK("twc",	"twc",			NULL,	16,	0x12c,	0x31E,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc1",	"spi_tegra.0",		NULL,	41,	0x134,	0x31E,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc2",	"spi_tegra.1",		NULL,	44,	0x118,	0x31E,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc3",	"spi_tegra.2",		NULL,	46,	0x11c,	0x31E,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc4",	"spi_tegra.3",		NULL,	68,	0x1b4,	0x31E,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("ide",	"ide",			NULL,	25,	0x144,	0x31E,	100000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* requires min voltage */
 	PERIPH_CLK("ndflash",	"tegra_nand",		NULL,	13,	0x160,	0x31E,	164000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
-	PERIPH_CLK("vfir",	"vfir",			NULL,	7,	0x168,	0x31E,	72000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
+	PERIPH_CLK("vfir",	"vfir",			NULL,	7,	0x168,	0x31E,	72000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("sdmmc1",	"sdhci-tegra.0",	NULL,	14,	0x150,	0x31E,	52000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
 	PERIPH_CLK("sdmmc2",	"sdhci-tegra.1",	NULL,	9,	0x154,	0x31E,	52000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
 	PERIPH_CLK("sdmmc3",	"sdhci-tegra.2",	NULL,	69,	0x1bc,	0x31E,	52000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
@@ -2158,22 +2178,22 @@ struct clk tegra_list_periph_clks[] = {
 	PERIPH_CLK("csite",	"csite",		NULL,	73,	0x1d4,	0x31E,	144000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* max rate ??? */
 	/* FIXME: what is la? */
 	PERIPH_CLK("la",	"la",			NULL,	76,	0x1f8,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("owr",	"tegra_w1",		NULL,	71,	0x1cc,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
+	PERIPH_CLK("owr",	"tegra_w1",		NULL,	71,	0x1cc,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("nor",	"nor",			NULL,	42,	0x1d0,	0x31E,	92000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* requires min voltage */
-	PERIPH_CLK("mipi",	"mipi",			NULL,	50,	0x174,	0x31E,	60000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
-	PERIPH_CLK("i2c1",	"tegra-i2c.0",		NULL,	12,	0x124,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("i2c2",	"tegra-i2c.1",		NULL,	54,	0x198,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("i2c3",	"tegra-i2c.2",		NULL,	67,	0x1b8,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("dvc",	"tegra-i2c.3",		NULL,	47,	0x128,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("i2c1_i2c",	"tegra-i2c.0",		"i2c",	0,	0,	0x31E,	72000000,  mux_pllp_out3,			0),
-	PERIPH_CLK("i2c2_i2c",	"tegra-i2c.1",		"i2c",	0,	0,	0x31E,	72000000,  mux_pllp_out3,			0),
-	PERIPH_CLK("i2c3_i2c",	"tegra-i2c.2",		"i2c",	0,	0,	0x31E,	72000000,  mux_pllp_out3,			0),
-	PERIPH_CLK("dvc_i2c",	"tegra-i2c.3",		"i2c",	0,	0,	0x31E,	72000000,  mux_pllp_out3,			0),
-	PERIPH_CLK("uarta",	"uart.0",		NULL,	6,	0x178,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX),
-	PERIPH_CLK("uartb",	"uart.1",		NULL,	7,	0x17c,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX),
-	PERIPH_CLK("uartc",	"uart.2",		NULL,	55,	0x1a0,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX),
-	PERIPH_CLK("uartd",	"uart.3",		NULL,	65,	0x1c0,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX),
-	PERIPH_CLK("uarte",	"uart.4",		NULL,	66,	0x1c4,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX),
+	PERIPH_CLK("mipi",	"mipi",			NULL,	50,	0x174,	0x31E,	60000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB), /* scales with voltage */
+	PERIPH_CLK("i2c1",	"tegra-i2c.0",		NULL,	12,	0x124,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("i2c2",	"tegra-i2c.1",		NULL,	54,	0x198,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("i2c3",	"tegra-i2c.2",		NULL,	67,	0x1b8,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("dvc",	"tegra-i2c.3",		NULL,	47,	0x128,	0x31E,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("i2c1_i2c",	"tegra-i2c.0",		"i2c",	0,	0,	0x31E,	72000000,  mux_pllp_out3,			PERIPH_ON_APB),
+	PERIPH_CLK("i2c2_i2c",	"tegra-i2c.1",		"i2c",	0,	0,	0x31E,	72000000,  mux_pllp_out3,			PERIPH_ON_APB),
+	PERIPH_CLK("i2c3_i2c",	"tegra-i2c.2",		"i2c",	0,	0,	0x31E,	72000000,  mux_pllp_out3,			PERIPH_ON_APB),
+	PERIPH_CLK("dvc_i2c",	"tegra-i2c.3",		"i2c",	0,	0,	0x31E,	72000000,  mux_pllp_out3,			PERIPH_ON_APB),
+	PERIPH_CLK("uarta",	"uart.0",		NULL,	6,	0x178,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | PERIPH_ON_APB),
+	PERIPH_CLK("uartb",	"uart.1",		NULL,	7,	0x17c,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | PERIPH_ON_APB),
+	PERIPH_CLK("uartc",	"uart.2",		NULL,	55,	0x1a0,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | PERIPH_ON_APB),
+	PERIPH_CLK("uartd",	"uart.3",		NULL,	65,	0x1c0,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | PERIPH_ON_APB),
+	PERIPH_CLK("uarte",	"uart.4",		NULL,	66,	0x1c4,	0x31E,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | PERIPH_ON_APB),
 	PERIPH_CLK("3d",	"3d",			NULL,	24,	0x158,	0x31E,	300000000, mux_pllm_pllc_pllp_plla,	MUX | DIV_U71 | PERIPH_MANUAL_RESET), /* scales with voltage and process_id */
 	PERIPH_CLK("2d",	"2d",			NULL,	21,	0x15c,	0x31E,	300000000, mux_pllm_pllc_pllp_plla,	MUX | DIV_U71), /* scales with voltage and process_id */
 	PERIPH_CLK("vi",	"tegra_camera",		"vi",	20,	0x148,	0x31E,	150000000, mux_pllm_pllc_pllp_plla,	MUX | DIV_U71), /* scales with voltage and process_id */