spi: Tegra2: Seaboard: fix UART corruption during SPI transactions

Simon Glass's proposal to fix this on Seaboard was NAK'd, so I removed his NS16550 references and added a small delay before SPI/UART muxing. Tested on my Seaboard with large SPI reads/writes and saw no corruption (crc's matched) and no spurious comm chars. Signed-off-by: Tom Warren <twarren@nvidia.com> Acked-by: Simon Glass <sjg@chromium.org> Tested-by: Jimmy Zhang <jimmzhang@nvidia.com>

spi: Tegra2: Seaboard: fix UART corruption during SPI transactions
Simon Glass's proposal to fix this on Seaboard was NAK'd, so I removed his NS16550 references and added a small delay before SPI/UART muxing. Tested on my Seaboard with large SPI reads/writes and saw no corruption (crc's matched) and no spurious comm chars. Signed-off-by: Tom Warren <twarren@nvidia.com> Acked-by: Simon Glass <sjg@chromium.org> Tested-by: Jimmy Zhang <jimmzhang@nvidia.com>
Tom Warren · Albert ARIBAUD
1 parent 558cd995d6
Showing 3 changed files with 21 additions and 23 deletions Side-by-side Diff
arch/arm/include/asm/arch-tegra2/uart-spi-switch.h
board/nvidia/common/uart-spi-switch.c
drivers/spi/tegra2_spi.c
@@ -29,7 +29,7 @@
  * time! If the board file provides this, the board config will declare it.
  * Let this be a lesson for others.
  */
-void pinmux_select_uart(NS16550_t regs);
+void pinmux_select_uart(void);
  
 /*
  * Signal that we are about the use the SPI bus.
@@ -38,7 +38,7 @@
  
 #else /* not CONFIG_SPI_UART_SWITCH */
  
-static inline void pinmux_select_uart(NS16550_t regs) {}
+static inline void pinmux_select_uart(void) {}
 static inline void pinmux_select_spi(void) {}
  
 #endif
@@ -21,7 +21,6 @@
  */
  
 #include <common.h>
-#include <ns16550.h>
 #include <asm/gpio.h>
 #include <asm/arch/pinmux.h>
 #include <asm/arch/uart-spi-switch.h>
@@ -40,7 +39,6 @@
 /* Information about the spi/uart switch */
 struct spi_uart {
 	int gpio;                       /* GPIO to control switch */
-	NS16550_t regs;                 /* Address of UART affected */
 	u32 port;                       /* Port number of UART affected */
 };
  
@@ -52,7 +50,6 @@
 {
 #if defined CONFIG_SPI_CORRUPTS_UART
 	config->gpio = CONFIG_UART_DISABLE_GPIO;
-	config->regs = (NS16550_t)CONFIG_SPI_CORRUPTS_UART;
 	config->port = CONFIG_SPI_CORRUPTS_UART_NR;
 #else
 	config->gpio = -1;
  
  
  
  
@@ -101,34 +98,24 @@
 	if (switch_pos == SWITCH_BOTH || new_pos == switch_pos)
 		return;
  
-	/* if the UART was selected, allow it to drain */
-	if (switch_pos == SWITCH_UART)
-		NS16550_drain(config->regs, config->port);
+	/* pre-delay, allow SPI/UART to settle, FIFO to empty, etc. */
+	udelay(CONFIG_SPI_CORRUPTS_UART_DLY);
  
 	/* We need to dynamically change the pinmux, shared w/UART RXD/CTS */
 	pinmux_set_func(PINGRP_GMC, new_pos == SWITCH_SPI ?
 				PMUX_FUNC_SFLASH : PMUX_FUNC_UARTD);
  
 	/*
-	* On Seaboard, MOSI/MISO are shared w/UART.
-	* Use GPIO I3 (UART_DISABLE) to tristate UART during SPI activity.
-	* Enable UART later (cs_deactivate) so we can use it for U-Boot comms.
-	*/
+	 * On Seaboard, MOSI/MISO are shared w/UART.
+	 * Use GPIO I3 (UART_DISABLE) to tristate UART during SPI activity.
+	 * Enable UART later (cs_deactivate) so we can use it for U-Boot comms.
+	 */
 	gpio_direction_output(config->gpio, new_pos == SWITCH_SPI);
 	switch_pos = new_pos;
-
-	/* if the SPI was selected, clear any junk bytes in the UART */
-	if (switch_pos == SWITCH_UART) {
-		/* TODO: What if it is part-way through clocking in junk? */
-		udelay(100);
-		NS16550_clear(config->regs, config->port);
-	}
 }
  
-void pinmux_select_uart(NS16550_t regs)
+void pinmux_select_uart(void)
 {
-	/* Also prevents calling spi_uart_switch() before relocation */
-	if (regs == local.regs)
 		spi_uart_switch(&local, SWITCH_UART);
 }
  
@@ -28,13 +28,18 @@
 #include <spi.h>
 #include <asm/io.h>
 #include <asm/gpio.h>
-#include <ns16550.h>
 #include <asm/arch/clk_rst.h>
 #include <asm/arch/clock.h>
 #include <asm/arch/pinmux.h>
 #include <asm/arch/uart-spi-switch.h>
 #include <asm/arch/tegra2_spi.h>
  
+#if defined(CONFIG_SPI_CORRUPTS_UART)
+ #define corrupt_delay()	udelay(CONFIG_SPI_CORRUPTS_UART_DLY);
+#else
+ #define corrupt_delay()
+#endif
+
 struct tegra_spi_slave {
 	struct spi_slave slave;
 	struct spi_tegra *regs;
  
  
@@ -161,14 +166,20 @@
  
 	/* CS is negated on Tegra, so drive a 1 to get a 0 */
 	setbits_le32(&spi->regs->command, SPI_CMD_CS_VAL);
+
+	corrupt_delay();		/* Let UART settle */
 }
  
 void spi_cs_deactivate(struct spi_slave *slave)
 {
 	struct tegra_spi_slave *spi = to_tegra_spi(slave);
  
+	pinmux_select_uart();
+
 	/* CS is negated on Tegra, so drive a 0 to get a 1 */
 	clrbits_le32(&spi->regs->command, SPI_CMD_CS_VAL);
+
+	corrupt_delay();		/* Let SPI settle */
 }
  
 int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
...	...	@@ -29,7 +29,7 @@
29	29	* time! If the board file provides this, the board config will declare it.
30	30	* Let this be a lesson for others.
31	31	*/
32		-void pinmux_select_uart(NS16550_t regs);
	32	+void pinmux_select_uart(void);
33	33
34	34	/*
35	35	* Signal that we are about the use the SPI bus.
...	...	@@ -38,7 +38,7 @@
38	38
39	39	#else /* not CONFIG_SPI_UART_SWITCH */
40	40
41		-static inline void pinmux_select_uart(NS16550_t regs) {}
	41	+static inline void pinmux_select_uart(void) {}
42	42	static inline void pinmux_select_spi(void) {}
43	43
44	44	#endif
...	...	@@ -21,7 +21,6 @@
21	21	*/
22	22
23	23	#include <common.h>
24		-#include <ns16550.h>
25	24	#include <asm/gpio.h>
26	25	#include <asm/arch/pinmux.h>
27	26	#include <asm/arch/uart-spi-switch.h>
...	...	@@ -40,7 +39,6 @@
40	39	/* Information about the spi/uart switch */
41	40	struct spi_uart {
42	41	int gpio; /* GPIO to control switch */
43		- NS16550_t regs; /* Address of UART affected */
44	42	u32 port; /* Port number of UART affected */
45	43	};
46	44
...	...	@@ -52,7 +50,6 @@
52	50	{
53	51	#if defined CONFIG_SPI_CORRUPTS_UART
54	52	config->gpio = CONFIG_UART_DISABLE_GPIO;
55		- config->regs = (NS16550_t)CONFIG_SPI_CORRUPTS_UART;
56	53	config->port = CONFIG_SPI_CORRUPTS_UART_NR;
57	54	#else
58	55	config->gpio = -1;
59	56
60	57
61	58
62	59
...	...	@@ -101,34 +98,24 @@
101	98	if (switch_pos == SWITCH_BOTH \|\| new_pos == switch_pos)
102	99	return;
103	100
104		- /* if the UART was selected, allow it to drain */
105		- if (switch_pos == SWITCH_UART)
106		- NS16550_drain(config->regs, config->port);
	101	+ /* pre-delay, allow SPI/UART to settle, FIFO to empty, etc. */
	102	+ udelay(CONFIG_SPI_CORRUPTS_UART_DLY);
107	103
108	104	/* We need to dynamically change the pinmux, shared w/UART RXD/CTS */
109	105	pinmux_set_func(PINGRP_GMC, new_pos == SWITCH_SPI ?
110	106	PMUX_FUNC_SFLASH : PMUX_FUNC_UARTD);
111	107
112	108	/*
113		- * On Seaboard, MOSI/MISO are shared w/UART.
114		- * Use GPIO I3 (UART_DISABLE) to tristate UART during SPI activity.
115		- * Enable UART later (cs_deactivate) so we can use it for U-Boot comms.
116		- */
	109	+ * On Seaboard, MOSI/MISO are shared w/UART.
	110	+ * Use GPIO I3 (UART_DISABLE) to tristate UART during SPI activity.
	111	+ * Enable UART later (cs_deactivate) so we can use it for U-Boot comms.
	112	+ */
117	113	gpio_direction_output(config->gpio, new_pos == SWITCH_SPI);
118	114	switch_pos = new_pos;
119		-
120		- /* if the SPI was selected, clear any junk bytes in the UART */
121		- if (switch_pos == SWITCH_UART) {
122		- /* TODO: What if it is part-way through clocking in junk? */
123		- udelay(100);
124		- NS16550_clear(config->regs, config->port);
125		- }
126	115	}
127	116
128		-void pinmux_select_uart(NS16550_t regs)
	117	+void pinmux_select_uart(void)
129	118	{
130		- /* Also prevents calling spi_uart_switch() before relocation */
131		- if (regs == local.regs)
132	119	spi_uart_switch(&local, SWITCH_UART);
133	120	}
134	121
...	...	@@ -28,13 +28,18 @@
28	28	#include <spi.h>
29	29	#include <asm/io.h>
30	30	#include <asm/gpio.h>
31		-#include <ns16550.h>
32	31	#include <asm/arch/clk_rst.h>
33	32	#include <asm/arch/clock.h>
34	33	#include <asm/arch/pinmux.h>
35	34	#include <asm/arch/uart-spi-switch.h>
36	35	#include <asm/arch/tegra2_spi.h>
37	36
	37	+#if defined(CONFIG_SPI_CORRUPTS_UART)
	38	+ #define corrupt_delay() udelay(CONFIG_SPI_CORRUPTS_UART_DLY);
	39	+#else
	40	+ #define corrupt_delay()
	41	+#endif
	42	+
38	43	struct tegra_spi_slave {
39	44	struct spi_slave slave;
40	45	struct spi_tegra *regs;
41	46
42	47
...	...	@@ -161,14 +166,20 @@
161	166
162	167	/* CS is negated on Tegra, so drive a 1 to get a 0 */
163	168	setbits_le32(&spi->regs->command, SPI_CMD_CS_VAL);
	169	+
	170	+ corrupt_delay(); /* Let UART settle */
164	171	}
165	172
166	173	void spi_cs_deactivate(struct spi_slave *slave)
167	174	{
168	175	struct tegra_spi_slave *spi = to_tegra_spi(slave);
169	176
	177	+ pinmux_select_uart();
	178	+
170	179	/* CS is negated on Tegra, so drive a 0 to get a 1 */
171	180	clrbits_le32(&spi->regs->command, SPI_CMD_CS_VAL);
	181	+
	182	+ corrupt_delay(); /* Let SPI settle */
172	183	}
173	184
174	185	int spi_xfer(struct spi_slave *slave, unsigned int bitlen,