[PATCH] i2c: cadence: Add standard bus recovery support

From: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
To: <linux-i2c@vger.kernel.org>
Cc: <michal.simek@xilinx.com>, <git@amd.com>, <git@xilinx.com>
Subject: [PATCH] i2c: cadence: Add standard bus recovery support
Date: Thu, 30 Jun 2022 17:48:28 +0530	[thread overview]
Message-ID: <1656591508-16313-1-git-send-email-shubhrajyoti.datta@xilinx.com> (raw)

From: Robert Hancock <robert.hancock@calian.com>

Hook up the standard GPIO/pinctrl-based recovery support..
In the discurssion
https://patchwork.ozlabs.org/project/linux-i2c/patch/20211129090116.16628-1-shubhrajyoti.datta@xilinx.com/

recovery should be done at the beginning of the transaction.
Here we are doing the recovery at the beginning on a timeout.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
---
 drivers/i2c/busses/i2c-cadence.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
index b4c1ad19cdae..cf15eca1f9e4 100644
--- a/drivers/i2c/busses/i2c-cadence.c
+++ b/drivers/i2c/busses/i2c-cadence.c
@@ -10,6 +10,7 @@
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
@@ -125,6 +126,8 @@
 #define CDNS_I2C_DIVB_MAX	64
 
 #define CDNS_I2C_TIMEOUT_MAX	0xFF
+#define CDNS_I2C_POLL_US	100000
+#define CDNS_I2C_TIMEOUT_US	500000
 
 #define CDNS_I2C_BROKEN_HOLD_BIT	BIT(0)
 
@@ -179,6 +182,7 @@ enum cdns_i2c_slave_state {
  * @clk_rate_change_nb:	Notifier block for clock rate changes
  * @quirks:		flag for broken hold bit usage in r1p10
  * @ctrl_reg:		Cached value of the control register.
+ * @rinfo:		Structure holding recovery information.
  * @ctrl_reg_diva_divb: value of fields DIV_A and DIV_B from CR register
  * @slave:		Registered slave instance.
  * @dev_mode:		I2C operating role(master/slave).
@@ -204,6 +208,7 @@ struct cdns_i2c {
 	struct notifier_block clk_rate_change_nb;
 	u32 quirks;
 	u32 ctrl_reg;
+	struct i2c_bus_recovery_info rinfo;
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 	u16 ctrl_reg_diva_divb;
 	struct i2c_client *slave;
@@ -796,6 +801,7 @@ static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
 	/* Wait for the signal of completion */
 	time_left = wait_for_completion_timeout(&id->xfer_done, msg_timeout);
 	if (time_left == 0) {
+		i2c_recover_bus(adap);
 		cdns_i2c_master_reset(adap);
 		dev_err(id->adap.dev.parent,
 				"timeout waiting on completion\n");
@@ -852,8 +858,12 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 #endif
 
 	/* Check if the bus is free */
-	if (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & CDNS_I2C_SR_BA) {
+	ret = readl_poll_timeout(id->membase + CDNS_I2C_SR_OFFSET, reg,
+				 !(reg & CDNS_I2C_SR_BA),
+				 CDNS_I2C_POLL_US, CDNS_I2C_TIMEOUT_US);
+	if (ret) {
 		ret = -EAGAIN;
+		i2c_recover_bus(adap);
 		goto out;
 	}
 
@@ -1278,6 +1288,7 @@ static int cdns_i2c_probe(struct platform_device *pdev)
 	id->adap.retries = 3;		/* Default retry value. */
 	id->adap.algo_data = id;
 	id->adap.dev.parent = &pdev->dev;
+	id->adap.bus_recovery_info = &id->rinfo;
 	init_completion(&id->xfer_done);
 	snprintf(id->adap.name, sizeof(id->adap.name),
 		 "Cadence I2C at %08lx", (unsigned long)r_mem->start);
-- 
2.17.1

