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 830481

Change-Id: I7f9f68f4cd6d39cf0bd697ddd236c4ce733dcf43
Reviewed-on: http://git-master/r/34413
Reviewed-by: Niket Sirsi <nsirsi@nvidia.com>
Tested-by: Niket Sirsi <nsirsi@nvidia.com>

1 files changed, 56 insertions, 34 deletions

diff --git a/arch/arm/mach-tegra/tegra3_clocks.c b/arch/arm/mach-tegra/tegra3_clocks.c
index a28bc7a849b0..1d3fc1042db4 100644
--- a/arch/arm/mach-tegra/tegra3_clocks.c
+++ b/arch/arm/mach-tegra/tegra3_clocks.c
@@ -320,6 +320,9 @@ static const struct utmi_clk_param utmi_parameters[] =
 
 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);
+
+#define MISC_GP_HIDREV                  0x804
 
 /*
  * Some peripheral clocks share an enable bit, so refcount the enable bits
@@ -335,6 +338,8 @@ static int tegra_periph_clk_enable_refcount[CLK_OUT_ENB_NUM * 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)
 
 #define clk_writel_delay(value, reg) 					\
 	do {								\
@@ -342,6 +347,7 @@ static int tegra_periph_clk_enable_refcount[CLK_OUT_ENB_NUM * 32];
 		udelay(2);						\
 	} while (0)
 
+
 static inline int clk_set_div(struct clk *c, int n)
 {
 	return clk_set_rate(c, (clk_get_rate(c->parent) + n-1) / n);
@@ -1856,26 +1862,42 @@ static int tegra3_periph_clk_enable(struct clk *c)
 
 static void tegra3_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_delay(
 			PERIPH_CLK_TO_BIT(c), PERIPH_CLK_TO_ENB_CLR_REG(c));
+	}
 }
 
 static void tegra3_periph_clk_reset(struct clk *c, bool assert)
 {
+	unsigned long val;
 	pr_debug("%s %s on clock %s\n", __func__,
 		 assert ? "assert" : "deassert", c->name);
 
 	if (!(c->flags & PERIPH_NO_RESET)) {
-		if (assert)
+		if (assert) {
+			/* 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_BIT(c),
 				   PERIPH_CLK_TO_RST_SET_REG(c));
-		else
+		} else
 			clk_writel(PERIPH_CLK_TO_BIT(c),
 				   PERIPH_CLK_TO_RST_CLR_REG(c));
 	}
@@ -3432,19 +3454,19 @@ static struct clk tegra_clk_emc = {
 	}
 struct clk tegra_list_clks[] = {
 	PERIPH_CLK("apbdma",	"apbdma",	    "apbdma",	34,	0,	26000000,  mux_clk_m,			0),
-	PERIPH_CLK("rtc",	"rtc-tegra",		NULL,	4,	0,	32768,     mux_clk_32k,			PERIPH_NO_RESET),
-	PERIPH_CLK("kbc",	"tegra-kbc",		NULL,	36,	0,	32768,	   mux_clk_32k, 		PERIPH_NO_RESET),
+	PERIPH_CLK("rtc",	"rtc-tegra",		NULL,	4,	0,	32768,     mux_clk_32k,			PERIPH_NO_RESET | PERIPH_ON_APB),
+	PERIPH_CLK("kbc",	"tegra-kbc",		NULL,	36,	0,	32768,	   mux_clk_32k, 		PERIPH_NO_RESET | PERIPH_ON_APB),
 	PERIPH_CLK("timer",	"timer",		NULL,	5,	0,	26000000,  mux_clk_m,			0),
 	PERIPH_CLK("kfuse",	"kfuse-tegra",		NULL,	40,	0,	26000000,  mux_clk_m,			0),
 	PERIPH_CLK("apbif",	"apbif",		NULL,	107,	0,	26000000,  mux_clk_m,			0),
-	PERIPH_CLK("i2s0",      "i2s.4",		NULL,   30,	0x1d8,	26000000,  mux_pllaout0_audio0_2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("i2s1",	"i2s.0",		NULL,	11,	0x100,	26000000,  mux_pllaout0_audio1_2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("i2s2",	"i2s.1",		NULL,	18,	0x104,	26000000,  mux_pllaout0_audio2_2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("i2s3",      "i2s.2",		NULL,   101,	0x3bc,	26000000,  mux_pllaout0_audio3_2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("i2s4",      "i2s.3",		NULL,   102,	0x3c0,	26000000,  mux_pllaout0_audio4_2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("spdif_out",	"spdif_out",		NULL,	10,	0x108,	100000000, mux_pllaout0_audio_2x_pllp_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("spdif_in",	"spdif_in",		NULL,	10,	0x10c,	100000000, mux_pllp_pllc_pllm,		MUX | DIV_U71),
-	PERIPH_CLK("pwm",	"pwm",			NULL,	17,	0x110,	432000000, mux_pllp_pllc_clk32_clkm,	MUX | MUX_PWM | DIV_U71),
+	PERIPH_CLK("i2s0",      "i2s.4",		NULL,   30,	0x1d8,	26000000,  mux_pllaout0_audio0_2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("i2s1",	"i2s.0",		NULL,	11,	0x100,	26000000,  mux_pllaout0_audio1_2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("i2s2",	"i2s.1",		NULL,	18,	0x104,	26000000,  mux_pllaout0_audio2_2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("i2s3",      "i2s.2",		NULL,   101,	0x3bc,	26000000,  mux_pllaout0_audio3_2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("i2s4",      "i2s.3",		NULL,   102,	0x3c0,	26000000,  mux_pllaout0_audio4_2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("spdif_out",	"spdif_out",		NULL,	10,	0x108,	100000000, mux_pllaout0_audio_2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("spdif_in",	"spdif_in",		NULL,	10,	0x10c,	100000000, mux_pllp_pllc_pllm,		MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("pwm",	"pwm",			NULL,	17,	0x110,	432000000, mux_pllp_pllc_clk32_clkm,	MUX | MUX_PWM | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("d_audio",	"d_audio",		NULL,   106,	0x3d0,	48000000,  mux_plla_pllc_pllp_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("dam0",	"dam.0",		NULL,   108,	0x3d8,	48000000,  mux_plla_pllc_pllp_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("dam1",	"dam.1",		NULL,   109,	0x3dc,	48000000,  mux_plla_pllc_pllp_clkm,	MUX | DIV_U71),
@@ -3453,19 +3475,19 @@ struct clk tegra_list_clks[] = {
 	PERIPH_CLK("hda2codec_2x",	"hda2codec_2x",	NULL,   111,	0x3e4,	48000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("hda2hdmi",	"hda2hdmi",		NULL,	128,	0,	48000000,  mux_clk_m,			0),
 	PERIPH_CLK("xio",	"xio",			NULL,	45,	0x120,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("twc",	"twc",			NULL,	16,	0x12c,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc1",	"spi_tegra.0",		NULL,	41,	0x134,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc2",	"spi_tegra.1",		NULL,	44,	0x118,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc3",	"spi_tegra.2",		NULL,	46,	0x11c,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc4",	"spi_tegra.3",		NULL,	68,	0x1b4,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc5",	"spi_tegra.4",		NULL,	104,	0x3c8,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("sbc6",	"spi_tegra.5",		NULL,	105,	0x3cc,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
+	PERIPH_CLK("twc",	"twc",			NULL,	16,	0x12c,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc1",	"spi_tegra.0",		NULL,	41,	0x134,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc2",	"spi_tegra.1",		NULL,	44,	0x118,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc3",	"spi_tegra.2",		NULL,	46,	0x11c,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc4",	"spi_tegra.3",		NULL,	68,	0x1b4,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc5",	"spi_tegra.4",		NULL,	104,	0x3c8,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("sbc6",	"spi_tegra.5",		NULL,	105,	0x3cc,	160000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("sata_oob",	"tegra_sata_oob",	NULL,	123,	0x420,	216000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("sata",	"tegra_sata",		NULL,	124,	0x424,	216000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("sata_cold",	"tegra_sata_cold",	NULL,	129,	0,	48000000,  mux_clk_m,			0),
 	PERIPH_CLK_EX("ndflash","tegra_nand",		NULL,	13,	0x160,	240000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71,	&tegra_nand_clk_ops),
 	PERIPH_CLK("ndspeed",	"tegra_nand_speed",	NULL,	80,	0x3f8,	240000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("vfir",	"vfir",			NULL,	7,	0x168,	72000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
+	PERIPH_CLK("vfir",	"vfir",			NULL,	7,	0x168,	72000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("sdmmc1",	"sdhci-tegra.0",	NULL,	14,	0x150,	208000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
 	PERIPH_CLK("sdmmc2",	"sdhci-tegra.1",	NULL,	9,	0x154,	104000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
 	PERIPH_CLK("sdmmc3",	"sdhci-tegra.2",	NULL,	69,	0x1bc,	208000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
@@ -3476,19 +3498,19 @@ struct clk tegra_list_clks[] = {
 	PERIPH_CLK("vde",	"tegra-avp",		"vde",	61,	0x1c8,	520000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_INT),
 	PERIPH_CLK("csite",	"csite",		NULL,	73,	0x1d4,	144000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* max rate ??? */
 	PERIPH_CLK("la",	"la",			NULL,	76,	0x1f8,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
-	PERIPH_CLK("owr",	"tegra_w1",		NULL,	71,	0x1cc,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
+	PERIPH_CLK("owr",	"tegra_w1",		NULL,	71,	0x1cc,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("nor",	"nor",			NULL,	42,	0x1d0,	127000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* requires min voltage */
-	PERIPH_CLK("mipi",	"mipi",			NULL,	50,	0x174,	60000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71), /* scales with voltage */
-	PERIPH_CLK("i2c1",	"tegra-i2c.0",		NULL,	12,	0x124,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("i2c2",	"tegra-i2c.1",		NULL,	54,	0x198,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("i2c3",	"tegra-i2c.2",		NULL,	67,	0x1b8,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("i2c4",	"tegra-i2c.3",		NULL,	103,	0x3c4,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("i2c5",	"tegra-i2c.4",		NULL,	47,	0x128,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16),
-	PERIPH_CLK("uarta",	"uart.0",		NULL,	6,	0x178,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART),
-	PERIPH_CLK("uartb",	"uart.1",		NULL,	7,	0x17c,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART),
-	PERIPH_CLK("uartc",	"uart.2",		NULL,	55,	0x1a0,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART),
-	PERIPH_CLK("uartd",	"uart.3",		NULL,	65,	0x1c0,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART),
-	PERIPH_CLK("uarte",	"uart.4",		NULL,	66,	0x1c4,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART),
+	PERIPH_CLK("mipi",	"mipi",			NULL,	50,	0x174,	60000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | PERIPH_ON_APB), /* scales with voltage */
+	PERIPH_CLK("i2c1",	"tegra-i2c.0",		NULL,	12,	0x124,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("i2c2",	"tegra-i2c.1",		NULL,	54,	0x198,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("i2c3",	"tegra-i2c.2",		NULL,	67,	0x1b8,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("i2c4",	"tegra-i2c.3",		NULL,	103,	0x3c4,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("i2c5",	"tegra-i2c.4",		NULL,	47,	0x128,	26000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U16 | PERIPH_ON_APB),
+	PERIPH_CLK("uarta",	"uart.0",		NULL,	6,	0x178,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART | PERIPH_ON_APB),
+	PERIPH_CLK("uartb",	"uart.1",		NULL,	7,	0x17c,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART | PERIPH_ON_APB),
+	PERIPH_CLK("uartc",	"uart.2",		NULL,	55,	0x1a0,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART | PERIPH_ON_APB),
+	PERIPH_CLK("uartd",	"uart.3",		NULL,	65,	0x1c0,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART | PERIPH_ON_APB),
+	PERIPH_CLK("uarte",	"uart.4",		NULL,	66,	0x1c4,	600000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71 | DIV_U71_UART | PERIPH_ON_APB),
 	PERIPH_CLK("3d",	"3d",			NULL,	24,	0x158,	520000000, mux_pllm_pllc_pllp_plla,	MUX | DIV_U71 | DIV_U71_INT | PERIPH_MANUAL_RESET),
 	PERIPH_CLK("3d2",       "3d2",			NULL,	98,	0x3b0,	520000000, mux_pllm_pllc_pllp_plla,	MUX | DIV_U71 | DIV_U71_INT | PERIPH_MANUAL_RESET),
 	PERIPH_CLK("2d",	"2d",			NULL,	21,	0x15c,	520000000, mux_pllm_pllc_pllp_plla,	MUX | DIV_U71 | DIV_U71_INT),
@@ -3517,7 +3539,7 @@ struct clk tegra_list_clks[] = {
 	PERIPH_CLK("extern1",	"extern1",		NULL,	120,	0x3ec,	216000000, mux_plla_clk32_pllp_clkm_plle,	MUX | MUX8 | DIV_U71),
 	PERIPH_CLK("extern2",	"extern2",		NULL,	121,	0x3f0,	216000000, mux_plla_clk32_pllp_clkm_plle,	MUX | MUX8 | DIV_U71),
 	PERIPH_CLK("extern3",	"extern3",		NULL,	122,	0x3f4,	216000000, mux_plla_clk32_pllp_clkm_plle,	MUX | MUX8 | DIV_U71),
-	PERIPH_CLK("i2cslow",	"i2cslow",		NULL,	81,	0x3fc,	26000000,  mux_pllp_pllc_clk32_clkm,	MUX | DIV_U71),
+	PERIPH_CLK("i2cslow",	"i2cslow",		NULL,	81,	0x3fc,	26000000,  mux_pllp_pllc_clk32_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("pcie",	"tegra-pcie",		"pcie",	70,	0,	250000000, mux_clk_m, 			0),
 	PERIPH_CLK("afi",	"tegra-pcie",		"afi",	72,	0,	250000000, mux_clk_m, 			0),
 	PERIPH_CLK("se",	"tegra-se",		NULL,	127,	0x42c,	520000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71| DIV_U71_INT),