linux-kernel - [PATCH 1/2] i2c: smbus: pass write disabling bit to spd instantiating function

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Message-Id: <20250424-for-upstream-i801-spd5118-no-instantiate-v1-1-627398268a1f@canonical.com>
Date: Thu, 24 Apr 2025 11:35:43 +0800
From: "Yo-Jung (Leo) Lin" <leo.lin@...onical.com>
To: Jean Delvare <jdelvare@...e.com>, Andi Shyti <andi.shyti@...nel.org>, 
 Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: Guenter Roeck <linux@...ck-us.net>, 
 "Chia-Lin Kao (AceLan)" <acelan.kao@...onical.com>, 
 linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org, 
 "Yo-Jung Lin (Leo)" <leo.lin@...onical.com>
Subject: [PATCH 1/2] i2c: smbus: pass write disabling bit to spd
 instantiating function

Some SMBus controllers may restrict writes to addresses where SPD
sensors may reside. This may lead to some SPD sensors not functioning
correctly, and might need extra handling. Pass this extra context to
i2c_register_spd() so that it could be handled accordingly.

Signed-off-by: Yo-Jung (Leo) Lin <leo.lin@...onical.com>
---
 drivers/i2c/busses/i2c-i801.c  | 6 ++++--
 drivers/i2c/busses/i2c-piix4.c | 2 +-
 drivers/i2c/i2c-smbus.c        | 2 +-
 include/linux/i2c-smbus.h      | 4 ++--
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 48e1af544b75..95619eb5e798 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -1180,7 +1180,8 @@ static void i801_probe_optional_targets(struct i801_priv *priv)
 #ifdef CONFIG_I2C_I801_MUX
 	if (!priv->mux_pdev)
 #endif
-		i2c_register_spd(&priv->adapter);
+		i2c_register_spd(&priv->adapter,
+				 !!(priv->original_hstcfg & SMBHSTCFG_SPD_WD));
 }
 #else
 static void __init input_apanel_init(void) {}
@@ -1283,7 +1284,8 @@ static int i801_notifier_call(struct notifier_block *nb, unsigned long action,
 		return NOTIFY_DONE;
 
 	/* Call i2c_register_spd for muxed child segments */
-	i2c_register_spd(to_i2c_adapter(dev));
+	i2c_register_spd(to_i2c_adapter(dev),
+			 !!(priv->original_hstcfg & SMBHSTCFG_SPD_WD));
 
 	return NOTIFY_OK;
 }
diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index dd75916157f0..085d121a88f6 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -971,7 +971,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
 	 * This would allow the ee1004 to be probed incorrectly.
 	 */
 	if (port == 0)
-		i2c_register_spd(adap);
+		i2c_register_spd(adap, false);
 
 	*padap = adap;
 	return 0;
diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index 7d40e7aa3799..97e833895dd7 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -372,7 +372,7 @@ EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);
  *  - Only works on systems with 1 to 8 memory slots
  */
 #if IS_ENABLED(CONFIG_DMI)
-void i2c_register_spd(struct i2c_adapter *adap)
+void i2c_register_spd(struct i2c_adapter *adap, bool write_disabled)
 {
 	int n, slot_count = 0, dimm_count = 0;
 	u16 handle;
diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h
index ced1c6ead52a..57bb3154eb47 100644
--- a/include/linux/i2c-smbus.h
+++ b/include/linux/i2c-smbus.h
@@ -44,9 +44,9 @@ static inline void i2c_free_slave_host_notify_device(struct i2c_client *client)
 #endif
 
 #if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_DMI)
-void i2c_register_spd(struct i2c_adapter *adap);
+void i2c_register_spd(struct i2c_adapter *adap, bool write_disabled);
 #else
-static inline void i2c_register_spd(struct i2c_adapter *adap) { }
+static inline void i2c_register_spd(struct i2c_adapter *adap, bool write_disabled) { }
 #endif
 
 #endif /* _LINUX_I2C_SMBUS_H */

-- 
2.43.0