V4L/DVB (8068): cx18: Add I2C slave reset via GPIO upon initialization

cx18: Add I2C slave reset via GPIO upon initialization.  One user,
Michael <msd4824@yahoo.com>, has reported this allows his HVR-1600 EEPROM to
be consistently recognized when using (long,) 100 msec delays.   The delays in
this commit are nominal (10 & 40 msec) and need testing/tuning on boards with
I2C problems to find the right values.
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/cx18/cx18-cards.c

@@ -82,6 +82,11 @@ static const struct cx18_card cx18_card_hvr1600_esmt = {
 	},
 	.gpio_init.initial_value = 0x3001,
 	.gpio_init.direction = 0x3001,
+	.gpio_i2c_slave_reset = {
+		.active_lo_mask = 0x3001,
+		.msecs_asserted = 10,
+		.msecs_recovery = 40,
+	},
 	.i2c = &cx18_i2c_std,
 };
 
@@ -122,6 +127,11 @@ static const struct cx18_card cx18_card_hvr1600_samsung = {
 	},
 	.gpio_init.initial_value = 0x3001,
 	.gpio_init.direction = 0x3001,
+	.gpio_i2c_slave_reset = {
+		.active_lo_mask = 0x3001,
+		.msecs_asserted = 10,
+		.msecs_recovery = 40,
+	},
 	.i2c = &cx18_i2c_std,
 };
 

drivers/media/video/cx18/cx18-cards.h

@@ -78,6 +78,13 @@ struct cx18_gpio_init { /* set initial GPIO DIR and OUT values */
 	u32 initial_value;
 };
 
+struct cx18_gpio_i2c_slave_reset {
+	u32 active_lo_mask; /* GPIO outputs that reset i2c chips when low */
+	u32 active_hi_mask; /* GPIO outputs that reset i2c chips when high */
+	int msecs_asserted; /* time period reset must remain asserted */
+	int msecs_recovery; /* time after deassert for chips to be ready */
+};
+
 struct cx18_card_tuner {
 	v4l2_std_id std; 	/* standard for which the tuner is suitable */
 	int 	    tuner; 	/* tuner ID (from tuner.h) */
@@ -115,6 +122,7 @@ struct cx18_card {
 	/* GPIO card-specific settings */
 	u8 xceive_pin; 		/* XCeive tuner GPIO reset pin */
 	struct cx18_gpio_init 		 gpio_init;
+	struct cx18_gpio_i2c_slave_reset gpio_i2c_slave_reset;
 
 	struct cx18_card_tuner tuners[CX18_CARD_MAX_TUNERS];
 	struct cx18_card_tuner_i2c *i2c;

drivers/media/video/cx18/cx18-gpio.c

@@ -53,10 +53,34 @@ static void gpio_write(struct cx18 *cx)
 	write_reg(((dir & 0xffff) << 16) | (val & 0xffff),
 			CX18_REG_GPIO_OUT1);
 	write_reg(dir & 0xffff0000, CX18_REG_GPIO_DIR2);
-	write_reg((dir & 0xffff0000) | ((val & 0xffff0000) >> 16),
+	write_reg_sync((dir & 0xffff0000) | ((val & 0xffff0000) >> 16),
 			CX18_REG_GPIO_OUT2);
 }
 
+void cx18_reset_i2c_slaves_gpio(struct cx18 *cx)
+{
+	const struct cx18_gpio_i2c_slave_reset *p;
+
+	p = &cx->card->gpio_i2c_slave_reset;
+
+	if ((p->active_lo_mask | p->active_hi_mask) == 0)
+		return;
+
+	/* Assuming that the masks are a subset of the bits in gpio_dir */
+
+	/* Assert */
+	cx->gpio_val =
+		(cx->gpio_val | p->active_hi_mask) & ~(p->active_lo_mask);
+	gpio_write(cx);
+	schedule_timeout_uninterruptible(msecs_to_jiffies(p->msecs_asserted));
+
+	/* Deassert */
+	cx->gpio_val =
+		(cx->gpio_val | p->active_lo_mask) & ~(p->active_hi_mask);
+	gpio_write(cx);
+	schedule_timeout_uninterruptible(msecs_to_jiffies(p->msecs_recovery));
+}
+
 void cx18_gpio_init(struct cx18 *cx)
 {
 	cx->gpio_dir = cx->card->gpio_init.direction;

drivers/media/video/cx18/cx18-gpio.h

@@ -21,4 +21,5 @@
  */
 
 void cx18_gpio_init(struct cx18 *cx);
+void cx18_reset_i2c_slaves_gpio(struct cx18 *cx);
 int cx18_reset_tuner_gpio(void *dev, int cmd, int value);

drivers/media/video/cx18/cx18-i2c.c

@@ -405,6 +405,8 @@ int init_cx18_i2c(struct cx18 *cx)
 	cx18_setscl(&cx->i2c_algo_cb_data[1], 1);
 	cx18_setsda(&cx->i2c_algo_cb_data[1], 1);
 
+	cx18_reset_i2c_slaves_gpio(cx);
+
 	return i2c_bit_add_bus(&cx->i2c_adap[0]) ||
 		i2c_bit_add_bus(&cx->i2c_adap[1]);
 }