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

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

Rebase-Id: R204c12464faad2d3e36fbd1b583e798fab99e248

1 files changed, 48 insertions, 27 deletions

diff --git a/arch/arm/mach-tegra/tegra2_clocks.c b/arch/arm/mach-tegra/tegra2_clocks.c
index 1bef372c5a8b..74dd0c14e732 100644
--- a/arch/arm/mach-tegra/tegra2_clocks.c
+++ b/arch/arm/mach-tegra/tegra2_clocks.c
@@ -155,6 +155,9 @@
 
 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 clocks share a register with other clocks.  Any clock op that
@@ -177,6 +180,8 @@ 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)
 {
@@ -1041,6 +1046,7 @@ out:
 static void tegra2_periph_clk_disable(struct clk *c)
 {
 	unsigned long flags;
+	unsigned long val;
 
 	pr_debug("%s on clock %s\n", __func__, c->name);
 
@@ -1052,9 +1058,16 @@ static void tegra2_periph_clk_disable(struct clk *c)
 	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));
+	}
 
 	spin_unlock_irqrestore(&clock_register_lock, flags);
 }
@@ -1062,15 +1075,23 @@ static void tegra2_periph_clk_disable(struct clk *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);
 
 	BUG_ON(!c->u.periph.clk_num);
 
-	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)
@@ -2264,25 +2285,25 @@ static struct clk tegra_clk_emc = {
 
 struct clk tegra_list_periph_clks[] = {
 	PERIPH_CLK("apbdma",	"tegra-dma",		NULL,	34,	0,	0x31E,	108000000, mux_pclk,			0),
-	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("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("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("kfuse",	"kfuse-tegra",		NULL,	40,	0,	0x31E,  26000000,  mux_clk_m,			0),
-	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("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 */
@@ -2294,18 +2315,18 @@ 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("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("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 */