Commit 4d6d35d3 authored by Yo-Jung (Leo) Lin's avatar Yo-Jung (Leo) Lin Committed by Andi Shyti
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i2c: smbus: introduce Write Disable-aware SPD instantiating functions 



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. Introduce new SPD-instantiating functions
that are aware of this, and use them instead.

Signed-off-by: default avatarYo-Jung Lin (Leo) <leo.lin@canonical.com>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20250430-for-upstream-i801-spd5118-no-instantiate-v2-1-2f54d91ae2c7@canonical.com


Signed-off-by: default avatarAndi Shyti <andi.shyti@kernel.org>
parent 8b284979

drivers/i2c/busses/i2c-i801.c

+2 −2
Original line number Diff line number Diff line
@@ -1180,7 +1180,7 @@ 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_write_enable(&priv->adapter);

}

#else

static void __init input_apanel_init(void) {}
@@ -1283,7 +1283,7 @@ 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_write_enable(to_i2c_adapter(dev));



	return NOTIFY_OK;

}

drivers/i2c/busses/i2c-piix4.c

+1 −1
Original line number Diff line number Diff line
@@ -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_write_enable(adap);



	*padap = adap;

	return 0;

drivers/i2c/i2c-smbus.c

+19 −2
Original line number Diff line number Diff line
@@ -372,12 +372,13 @@ 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)

static void i2c_register_spd(struct i2c_adapter *adap, bool write_disabled)

{

	int n, slot_count = 0, dimm_count = 0;

	u16 handle;

	u8 common_mem_type = 0x0, mem_type;

	u64 mem_size;

	bool instantiate = true;

	const char *name;



	while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) {
@@ -438,6 +439,7 @@ void i2c_register_spd(struct i2c_adapter *adap) 
	case 0x22:	/* DDR5 */

	case 0x23:	/* LPDDR5 */

		name = "spd5118";

		instantiate = !write_disabled;

		break;

	default:

		dev_info(&adap->dev,
@@ -461,6 +463,9 @@ void i2c_register_spd(struct i2c_adapter *adap) 
		addr_list[0] = 0x50 + n;

		addr_list[1] = I2C_CLIENT_END;



		if (!instantiate)

			continue;



		if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) {

			dev_info(&adap->dev,

				 "Successfully instantiated SPD at 0x%hx\n",
@@ -469,7 +474,19 @@ void i2c_register_spd(struct i2c_adapter *adap) 
		}

	}

}

EXPORT_SYMBOL_GPL(i2c_register_spd);



void i2c_register_spd_write_disable(struct i2c_adapter *adap)

{

	i2c_register_spd(adap, true);

}

EXPORT_SYMBOL_GPL(i2c_register_spd_write_disable);



void i2c_register_spd_write_enable(struct i2c_adapter *adap)

{

	i2c_register_spd(adap, false);

}

EXPORT_SYMBOL_GPL(i2c_register_spd_write_enable);



#endif



MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");

include/linux/i2c-smbus.h

+4 −2
Original line number Diff line number Diff line
@@ -44,9 +44,11 @@ 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_write_disable(struct i2c_adapter *adap);

void i2c_register_spd_write_enable(struct i2c_adapter *adap);

#else

static inline void i2c_register_spd(struct i2c_adapter *adap) { }

static inline void i2c_register_spd_write_disable(struct i2c_adapter *adap) { }

static inline void i2c_register_spd_write_enable(struct i2c_adapter *adap) { }

#endif



#endif /* _LINUX_I2C_SMBUS_H */