Merge patch series "Fix driver for misc/atsha204a"

Michał Barnaś <barnas@google.com> says:

Fix the driver to behave like the chip datasheet requires.
Improve wake up function to send low signal on SDA line for at least
60us as chip requires to wake up. Fix sleep function to move the chip
into sleep mode, not into idle mode. Remove unnecessary for loop,
which would never run for more than one iteration.

1 files changed, 61 insertions, 29 deletions

diff --git a/drivers/misc/atsha204a-i2c.c b/drivers/misc/atsha204a-i2c.c
index d3c5158..707daa9 100644
--- a/drivers/misc/atsha204a-i2c.c
+++ b/drivers/misc/atsha204a-i2c.c
@@ -21,7 +21,6 @@
 #include <linux/bitrev.h>
 #include <u-boot/crc.h>
 
-#define ATSHA204A_TWLO_US		60
 #define ATSHA204A_TWHI_US		2500
 #define ATSHA204A_TRANSACTION_TIMEOUT	100000
 #define ATSHA204A_TRANSACTION_RETRY	5
@@ -34,6 +33,48 @@ static inline u16 atsha204a_crc16(const u8 *buffer, size_t len)
 	return bitrev16(crc16(0, buffer, len));
 }
 
+static int atsha204a_ping_bus(struct udevice *dev)
+{
+	struct udevice *bus = dev_get_parent(dev);
+	struct i2c_msg msg;
+	int speed;
+	int res;
+	u8 val = 0;
+
+	speed = dm_i2c_get_bus_speed(bus);
+	if (speed != I2C_SPEED_STANDARD_RATE) {
+		int rv;
+
+		rv = dm_i2c_set_bus_speed(bus, I2C_SPEED_STANDARD_RATE);
+		if (rv)
+			debug("Couldn't change the I2C bus speed\n");
+	}
+
+	/*
+	 * The I2C drivers don't support sending messages when NAK is received.
+	 * This chip requires wake up low signal on SDA for >= 60us.
+	 * To achieve this, we slow the bus to 100kHz and send an empty
+	 * message to address 0. This will hold the SDA line low for the
+	 * required time to wake up the chip.
+	 */
+	msg.addr = 0;
+	msg.flags = I2C_M_STOP;
+	msg.len = sizeof(val);
+	msg.buf = &val;
+
+	res = dm_i2c_xfer(dev, &msg, 1);
+
+	if (speed != I2C_SPEED_STANDARD_RATE) {
+		int rv;
+
+		rv = dm_i2c_set_bus_speed(bus, speed);
+		if (rv)
+			debug("Couldn't restore the I2C bus speed\n");
+	}
+
+	return res;
+}
+
 static int atsha204a_send(struct udevice *dev, const u8 *buf, u8 len)
 {
 	fdt_addr_t *priv = dev_get_priv(dev);
@@ -94,42 +135,33 @@ static int atsha204a_recv_resp(struct udevice *dev,
 
 int atsha204a_wakeup(struct udevice *dev)
 {
-	u8 req[4];
 	struct atsha204a_resp resp;
-	int try, res;
+	int res;
 
 	debug("Waking up ATSHA204A\n");
 
-	for (try = 1; try <= 10; ++try) {
-		debug("Try %i... ", try);
+	/*
+	 * The device ignores any levels or transitions on the SCL pin
+	 * when the device is idle, asleep or during waking up.
+	 * Don't check for error when waking up the device.
+	 */
+	atsha204a_ping_bus(dev);
 
-		/*
-		 * The device ignores any levels or transitions on the SCL pin
-		 * when the device is idle, asleep or during waking up.
-		 * Don't check for error when waking up the device.
-		 */
-		memset(req, 0, 4);
-		atsha204a_send(dev, req, 4);
-
-		udelay(ATSHA204A_TWLO_US + ATSHA204A_TWHI_US);
-
-		res = atsha204a_recv_resp(dev, &resp);
-		if (res) {
-			debug("failed on receiving response, ending\n");
-			return res;
-		}
+	udelay(ATSHA204A_TWHI_US);
 
-		if (resp.code != ATSHA204A_STATUS_AFTER_WAKE) {
-			debug ("failed (responce code = %02x), ending\n",
-			       resp.code);
-			return -EBADMSG;
-		}
+	res = atsha204a_recv_resp(dev, &resp);
+	if (res) {
+		debug("failed on receiving response, ending\n");
+		return res;
+	}
 
-		debug("success\n");
-		return 0;
+	if (resp.code != ATSHA204A_STATUS_AFTER_WAKE) {
+		debug("failed (response code = %02x), ending\n", resp.code);
+		return -EBADMSG;
 	}
 
-	return -ETIMEDOUT;
+	debug("success\n");
+	return 0;
 }
 
 int atsha204a_idle(struct udevice *dev)
@@ -146,7 +178,7 @@ int atsha204a_idle(struct udevice *dev)
 int atsha204a_sleep(struct udevice *dev)
 {
 	int res;
-	u8 req = ATSHA204A_FUNC_IDLE;
+	u8 req = ATSHA204A_FUNC_SLEEP;
 
 	res = atsha204a_send(dev, &req, 1);
 	if (res)