[U-Boot] [PATCH v3 3/9] kmp204x: I2C deblocking support

[Valentin Longchamp]

From: Rainer Boschung <rainer.boschung at keymile.com>

This patch adds support for using some GPIOs that are connected to the
I2C bus to force the bus lines state and perform some bus deblocking
sequences.

The KM common deblocking algorithm from board/keymile/common/common.c is
used. The GPIO lines used for deblocking the I2C bus are some external
GPIOs provided by the QRIO CPLD:
  - SCL = GPIOA_20
  - SDA = GPIOA_21

The QRIO GPIOs act in an open-drain-like manner, for 0 the line is
driven low and for 1 the GPIO is set as input and the line gets
pulled-up.

Signed-off-by: Rainer Boschung <rainer.boschung at keymile.com>
Signed-off-by: Valentin Longchamp <valentin.longchamp at keymile.com>

---

Changes in v3:
- rewrite the commit message and and the comments for more clarity
- fix the GPIO numbers that where not correct

Changes in v2: None

 board/keymile/kmp204x/kmp204x.c     | 53 ++++++++++++++++++++++++++++++++++---
 include/configs/km/kmp204x-common.h | 10 +++++++
 2 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/board/keymile/kmp204x/kmp204x.c b/board/keymile/kmp204x/kmp204x.c
index bbb2453..726d26e 100644
--- a/board/keymile/kmp204x/kmp204x.c
+++ b/board/keymile/kmp204x/kmp204x.c
@@ -33,12 +33,51 @@ int checkboard(void)
 	return 0;
 }
 
-/* TODO: implement the I2C deblocking function */
-int i2c_make_abort(void)
+/* I2C deblocking uses the algorithm defined in board/keymile/common/common.c
+ * 2 dedicated QRIO GPIOs externally pull the SCL and SDA lines
+ * For I2C only the low state is activly driven and high state is pulled-up
+ * by a resistor. Therefore the deblock GPIOs are used
+ *  -> as an active output to drive a low state
+ *  -> as an open-drain input to have a pulled-up high state
+ */
+
+/* QRIO GPIOs used for deblocking */
+#define DEBLOCK_PORT1	GPIO_A
+#define DEBLOCK_SCL1	20
+#define DEBLOCK_SDA1	21
+
+/* By default deblock GPIOs are floating */
+static void i2c_deblock_gpio_cfg(void)
+{
+	/* set I2C bus 1 deblocking GPIOs input, but 0 value for open drain */
+	qrio_gpio_direction_input(DBLK_PORT1, DBLK_SCL1);
+	qrio_gpio_direction_input(DBLK_PORT1, DBLK_SDA1);
+
+	qrio_set_gpio(DBLK_PORT1, DBLK_SCL1, 0);
+	qrio_set_gpio(DBLK_PORT1, DBLK_SDA1, 0);
+}
+
+void set_sda(int state)
+{
+	qrio_set_opendrain_gpio(DBLK_PORT1, DBLK_SDA1, state);
+}
+
+void set_scl(int state)
+{
+	qrio_set_opendrain_gpio(DBLK_PORT1, DBLK_SCL1, state);
+}
+
+int get_sda(void)
+{
+	return qrio_get_gpio(DBLK_PORT1, DBLK_SDA1);
+}
+
+int get_scl(void)
 {
-	return 1;
+	return qrio_get_gpio(DBLK_PORT1, DBLK_SCL1);
 }
 
+
 #define ZL30158_RST	8
 #define ZL30343_RST	9
 
@@ -77,6 +116,14 @@ unsigned long get_board_sys_clk(unsigned long dummy)
 	return 66666666;
 }
 
+int misc_init_f(void)
+{
+	/* configure QRIO pis for i2c deblocking */
+	i2c_deblock_gpio_cfg();
+
+	return 0;
+}
+
 #define NUM_SRDS_BANKS	2
 #define PHY_RST		15
 
diff --git a/include/configs/km/kmp204x-common.h b/include/configs/km/kmp204x-common.h
index e33ac90..626879a 100644
--- a/include/configs/km/kmp204x-common.h
+++ b/include/configs/km/kmp204x-common.h
@@ -211,6 +211,7 @@ unsigned long get_board_sys_clk(unsigned long dummy);
 
 #define CONFIG_BOARD_EARLY_INIT_F
 #define CONFIG_BOARD_EARLY_INIT_R	/* call board_early_init_r function */
+#define CONFIG_MISC_INIT_F
 #define CONFIG_MISC_INIT_R
 #define CONFIG_LAST_STAGE_INIT
 
@@ -266,7 +267,10 @@ unsigned long get_board_sys_clk(unsigned long dummy);
 #define CONFIG_FIT_VERBOSE	/* enable fit_format_{error,warning}() */
 
 /* I2C */
+
 #define CONFIG_SYS_I2C
+#define CONFIG_SYS_I2C_INIT_BOARD
+#define CONFIG_SYS_I2C_SPEED		100000 /* deblocking */
 #define CONFIG_SYS_NUM_I2C_BUSES	3
 #define CONFIG_SYS_I2C_MAX_HOPS		1
 #define CONFIG_SYS_I2C_FSL		/* Use FSL I2C driver */
@@ -279,6 +283,12 @@ unsigned long get_board_sys_clk(unsigned long dummy);
 					{0, {{I2C_MUX_PCA9547, 0x70, 1 } } }, \
 					{0, {{I2C_MUX_PCA9547, 0x70, 2 } } }, \
 				}
+#ifndef __ASSEMBLY__
+void set_sda(int state);
+void set_scl(int state);
+int get_sda(void);
+int get_scl(void);
+#endif
 
 #define CONFIG_KM_IVM_BUS		1	/* I2C1 (Mux-Port 1)*/
 
-- 
1.8.0.1