recipes-kernel/linux/files/0001-i2c-npcm-quirk-to-fix-multiple-master-xfer-failure.patch

From 691895208e6ff75ed6866b2825e173685c77aabe Mon Sep 17 00:00:00 2001
From: Jinliang Wang <jinliangw@google.com>
Date: Tue, 28 Mar 2023 11:16:27 -0700
Subject: [PATCH] i2c: npcm: quirk to fix multiple master xfer failure

This patch is backported from Avi.Fishman@nuvoton.com and
tali.perry@nuvoton.com 's debug version driver v15.
Link (https://drive.google.com/corp/drive/folders/19RaTMJcarpN-dpuAlbTFPm_0xKx7TKjU?resourcekey=0-UI41jAZA4xd_5VINmDcN0Q)
It contains some quirk to detect MCTP packet and then apply some
special handling. Nuvoton is still trying to find a more proper way to
support multiple master mode in upstream i2c-npcm7xx.c.

Patch Tracking Bug: b/275108914
Upstream info / review: N/A
Upstream-Status: Pending
Justification: The patch is upstreamable however Nuvoton is still
working on more appropriate and general implementation

Google-Bug-Id: 266723609
Google-Bug-Id: 295580753
Google-Bug-Id: 297058513
Signed-off-by: William A. Kennington III <wak@google.com>
Signed-off-by: Jinliang Wang <jinliangw@google.com>
---
 drivers/i2c/busses/i2c-npcm7xx.c | 73 ++++++++++++++++++++++++++------
 1 file changed, 60 insertions(+), 13 deletions(-)

diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c
index 7e71b89bb1fd..05c0a1b32b0f 100644
--- a/drivers/i2c/busses/i2c-npcm7xx.c
+++ b/drivers/i2c/busses/i2c-npcm7xx.c
@@ -433,6 +433,8 @@ struct npcm_i2c {
 	bool read_block_use;
 	unsigned long int_time_stamp;
 	unsigned long bus_freq; /* in Hz */
+	bool multi_master;
+	int busy_cnt;
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 	u8 own_slave_addr;
 	struct i2c_client *slave;
@@ -800,6 +802,8 @@ static void npcm_i2c_reset(struct npcm_i2c *bus)
 	npcm_i2c_clear_master_status(bus);
 
 	bus->state = I2C_IDLE;
+	bus->busy_cnt = 0;
+	bus->multi_master = false;
 }
 
 static inline bool npcm_i2c_is_master(struct npcm_i2c *bus)
@@ -1215,7 +1219,7 @@ static irqreturn_t npcm_i2c_int_slave_handler(struct npcm_i2c *bus)
 		 * master ( for a channel which is master\slave switching)
 		 */
 		if (completion_done(&bus->cmd_complete) == false) {
-			bus->cmd_err = -EIO;
+			bus->cmd_err = -EAGAIN;
 			complete(&bus->cmd_complete);
 		}
 		bus->own_slave_addr = 0xFF;
@@ -1640,6 +1644,7 @@ static void npcm_i2c_irq_handle_ber(struct npcm_i2c *bus)
 	bus->stop_ind = I2C_BUS_ERR_IND;
 	if (npcm_i2c_is_master(bus)) {
 		npcm_i2c_master_abort(bus);
+		bus->cmd_err = -EAGAIN;
 	} else {
 		bus->ber_state = true;
 		npcm_i2c_clear_master_status(bus);
@@ -1822,11 +1827,16 @@ static int npcm_i2c_recovery_tgclk(struct i2c_adapter *_adap)
 	/* Allow 3 bytes (27 toggles) to be read from the slave: */
 	int              iter = 27;
 
+	bus->ber_state = false;
+
+	if (bus->multi_master) {
+		return 0;
+	}
+
 	if ((npcm_i2c_get_SDA(_adap) == 1) && (npcm_i2c_get_SCL(_adap) == 1)) {
 		dev_dbg(bus->dev, "bus%d-0x%x recovery skipped, bus not stuck",
 			bus->num, bus->dest_addr);
 		npcm_i2c_reset(bus);
-		bus->ber_state = false;
 		return 0;
 	}
 
@@ -1891,7 +1901,6 @@ static int npcm_i2c_recovery_tgclk(struct i2c_adapter *_adap)
 		if (bus->rec_succ_cnt < ULLONG_MAX)
 			bus->rec_succ_cnt++;
 	}
-	bus->ber_state = false;
 	return status;
 }
 
@@ -2110,7 +2119,7 @@ static bool npcm_i2c_master_start_xmit(struct npcm_i2c *bus,
 				       bool use_PEC, bool use_read_block)
 {
 	if (bus->state != I2C_IDLE) {
-		bus->cmd_err = -EBUSY;
+		bus->cmd_err = -EAGAIN;
 		return false;
 	}
 	bus->dest_addr = slave_addr << 1;
@@ -2168,6 +2177,7 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		return -EINVAL;
 	}
 
+	bus->multi_master = false;
 	msg0 = &msgs[0];
 	slave_addr = msg0->addr;
 	if (msg0->flags & I2C_M_RD) { /* read */
@@ -2187,6 +2197,11 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		write_data = msg0->buf;
 		nread = 0;
 		read_data = NULL;
+		if ((num == 1) && (nwrite > 7) && (write_data[0] == 0xF) && ((write_data[1] + 3) == nwrite))
+		{
+			printk_once("i2c%d: Met MCTP packet\n", bus->num);
+			bus->multi_master = true;
+		}
 		if (num == 2) {
 			msg1 = &msgs[1];
 			read_data = msg1->buf;
@@ -2204,6 +2219,7 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 
 	if (nwrite >= 32 * 1024 || nread >= 32 * 1024) {
 		dev_err(bus->dev, "i2c%d buffer too big\n", bus->num);
+		bus->multi_master = false;
 		return -EINVAL;
 	}
 
@@ -2215,7 +2231,7 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		 * entire while since it is too long.
 		 */
 		spin_lock_irqsave(&bus->lock, flags);
-		bus_busy = ioread8(bus->reg + NPCM_I2CCST) & NPCM_I2CCST_BB;
+		bus_busy = (ioread8(bus->reg + NPCM_I2CCST) & NPCM_I2CCST_BB) || (bus->state != I2C_IDLE);
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 		if (!bus_busy && bus->slave)
 			iowrite8((bus->slave->addr & 0x7F),
@@ -2223,21 +2239,41 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 #endif
 		spin_unlock_irqrestore(&bus->lock, flags);
 
-	} while (time_is_after_jiffies(time_left) && bus_busy);
+        if (time_is_after_jiffies(time_left) && bus_busy)
+            msleep_interruptible(10);
+        else
+            break;
+
+	} while (true);
 
 	bus->dest_addr = slave_addr << 1;
 	if (bus_busy || bus->ber_state) {
 		iowrite8(NPCM_I2CCST_BB, bus->reg + NPCM_I2CCST);
+		if (bus->multi_master) {
+			bus->busy_cnt++;
+			if (bus->busy_cnt < adap->retries) {
+				/* skip recovery */
+				bus->cmd_err = -EAGAIN;
+				goto npcm_i2c_xfer_complete;
+			}
+
+			/* need recovery */
+			dev_err(bus->dev, "i2c%d multi_master busy recover\n",
+				bus->num);
+		}
+
 		npcm_i2c_reset(bus);
 		i2c_recover_bus(adap);
-		return -EAGAIN;
+		bus->cmd_err = -EAGAIN;
+		goto npcm_i2c_xfer_complete;
 	}
 
 	npcm_i2c_init_params(bus);
 	bus->msgs = msgs;
 	bus->msgs_num = num;
-	bus->cmd_err = 0;
+	bus->cmd_err = -EAGAIN;
 	bus->read_block_use = read_block;
+	bus->busy_cnt = 0;
 
 	reinit_completion(&bus->cmd_complete);
 
@@ -2261,8 +2297,7 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			if (bus->timeout_cnt < ULLONG_MAX)
 				bus->timeout_cnt++;
 			if (bus->master_or_slave == I2C_MASTER) {
-				i2c_recover_bus(adap);
-				bus->cmd_err = -EIO;
+				bus->cmd_err = -EAGAIN;
 				bus->state = I2C_IDLE;
 			}
 		}
@@ -2270,7 +2305,7 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 
 	/* if there was BER, check if need to recover the bus: */
 	if (bus->cmd_err == -EAGAIN)
-		bus->cmd_err = i2c_recover_bus(adap);
+		i2c_recover_bus(adap);
 
 	/*
 	 * After any type of error, check if LAST bit is still set,
@@ -2285,6 +2320,15 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	npcm_i2c_stall_after_start(bus, false);
 	npcm_i2c_eob_int(bus, false);
 
+npcm_i2c_xfer_complete:
+	if (bus->multi_master) {
+		if ((bus->cmd_err <  0 && bus->cmd_err != -EAGAIN)||
+			(bus->cmd_err >= 0 && bus->cmd_err != num)){
+			dev_err(bus->dev, "i2c%d xfer returned %d\n", bus->num, bus->cmd_err);
+		}
+		/* reset it to false upon exit */
+		bus->multi_master = false;
+	}
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 	/* reenable slave if it was enabled */
 	if (bus->slave)
@@ -2426,8 +2470,11 @@ static int npcm_i2c_probe_bus(struct platform_device *pdev)
 
 	adap = &bus->adap;
 	adap->owner = THIS_MODULE;
-	adap->retries = 3;
-	adap->timeout = 2 * HZ;
+	/* 10 retries x 400 ms = 4 seconds(HZ) */
+	adap->retries = 10;
+	adap->timeout = msecs_to_jiffies(400) * adap->retries;
+	bus->multi_master = false;
+	bus->busy_cnt = 0;
 	adap->algo = &npcm_i2c_algo;
 	adap->quirks = &npcm_i2c_quirks;
 	adap->algo_data = bus;
-- 
2.42.0.820.g83a721a137-goog