linux/drivers/i2c, branch v6.17

i2c: rtl9300: Drop unsupported I2C_FUNC_SMBUS_I2C_BLOCK

2025-09-27T22:23:34Z

While applying the patch for commit ede965fd555a ("i2c: rtl9300: remove broken SMBus Quick operation support"), a conflict was incorrectly solved by adding the I2C_FUNC_SMBUS_I2C_BLOCK feature flag. But the code to handle I2C_SMBUS_I2C_BLOCK_DATA requests will be added by a separate commit. Fixes: ede965fd555a ("i2c: rtl9300: remove broken SMBus Quick operation support") Signed-off-by: Sven Eckelmann Signed-off-by: Wolfram Sang

i2c: riic: Allow setting frequencies lower than 50KHz

2025-09-23T19:14:53Z

The MR1.CKS field is 3 bits wide and all the possible values (from 0 to 7) are valid. This is true for all the SoCs currently integrated in upstream Linux. Take into account CKS=7 which allows setting bus frequencies lower than 50KHz. This may be useful at least for debugging. Fixes: d982d6651419 ("i2c: riic: remove clock and frequency restrictions") Signed-off-by: Claudiu Beznea Signed-off-by: Wolfram Sang

i2c: rtl9300: remove broken SMBus Quick operation support

2025-09-03T22:31:34Z

Remove the SMBus Quick operation from this driver because it is not natively supported by the hardware and is wrongly implemented in the driver. The I2C controllers in Realtek RTL9300 and RTL9310 are SMBus-compliant but there doesn't seem to be native support for the SMBus Quick operation. It is not explicitly mentioned in the documentation but looking at the registers which configure an SMBus transaction, one can see that the data length cannot be set to 0. This suggests that the hardware doesn't allow any SMBus message without data bytes (except for those it does on it's own, see SMBus Block Read). The current implementation of SMBus Quick operation passes a length of 0 (which is actually invalid). Before the fix of a bug in a previous commit, this led to a read operation of 16 bytes from any register (the one of a former transaction or any other value. This caused issues like soft-bricked SFP modules after a simple probe with i2cdetect which uses Quick by default. Running this with SFP modules whose EEPROM isn't write-protected, some of the initial bytes are overwritten because a 16-byte write operation is executed instead of a Quick Write. (This temporarily soft-bricked one of my DAC cables.) Because SMBus Quick operation is obviously not supported on these controllers (because a length of 0 cannot be set, even when no register address is set), remove that instead of claiming there is support. There also shouldn't be any kind of emulated 'Quick' which just does another kind of operation in the background. Otherwise, specific issues occur in case of a 'Quick' Write which actually writes unknown data to an unknown register. Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller") Cc: stable@vger.kernel.org # v6.13+ Signed-off-by: Jonas Jelonek Tested-by: Sven Eckelmann Reviewed-by: Chris Packham Tested-by: Chris Packham # On RTL9302C based board Tested-by: Markus Stockhausen Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250831100457.3114-4-jelonek.jonas@gmail.com

i2c: rtl9300: ensure data length is within supported range

2025-09-03T22:31:28Z

Add an explicit check for the xfer length to 'rtl9300_i2c_config_xfer' to ensure the data length isn't within the supported range. In particular a data length of 0 is not supported by the hardware and causes unintended or destructive behaviour. This limitation becomes obvious when looking at the register documentation [1]. 4 bits are reserved for DATA_WIDTH and the value of these 4 bits is used as N + 1, allowing a data length range of 1 <= len <= 16. Affected by this is the SMBus Quick Operation which works with a data length of 0. Passing 0 as the length causes an underflow of the value due to: (len - 1) & 0xf and effectively specifying a transfer length of 16 via the registers. This causes a 16-byte write operation instead of a Quick Write. For example, on SFP modules without write-protected EEPROM this soft-bricks them by overwriting some initial bytes. For completeness, also add a quirk for the zero length. [1] https://svanheule.net/realtek/longan/register/i2c_mst1_ctrl2 Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller") Cc: stable@vger.kernel.org # v6.13+ Signed-off-by: Jonas Jelonek Tested-by: Sven Eckelmann Reviewed-by: Chris Packham Tested-by: Chris Packham # On RTL9302C based board Tested-by: Markus Stockhausen Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250831100457.3114-3-jelonek.jonas@gmail.com

i2c: rtl9300: fix channel number bound check

2025-09-03T22:31:23Z

Fix the current check for number of channels (child nodes in the device tree). Before, this was: if (device_get_child_node_count(dev) >= RTL9300_I2C_MUX_NCHAN) RTL9300_I2C_MUX_NCHAN gives the maximum number of channels so checking with '>=' isn't correct because it doesn't allow the last channel number. Thus, fix it to: if (device_get_child_node_count(dev) > RTL9300_I2C_MUX_NCHAN) Issue occured on a TP-Link TL-ST1008F v2.0 device (8 SFP+ ports) and fix is tested there. Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller") Cc: stable@vger.kernel.org # v6.13+ Signed-off-by: Jonas Jelonek Tested-by: Sven Eckelmann Reviewed-by: Chris Packham Tested-by: Chris Packham # On RTL9302C based board Tested-by: Markus Stockhausen Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250831100457.3114-2-jelonek.jonas@gmail.com

i2c: i801: Hide Intel Birch Stream SoC TCO WDT

2025-09-02T16:22:29Z

Hide the Intel Birch Stream SoC TCO WDT feature since it was removed. On platforms with PCH TCO WDT, this redundant device might be rendering errors like this: [ 28.144542] sysfs: cannot create duplicate filename '/bus/platform/devices/iTCO_wdt' Fixes: 8c56f9ef25a3 ("i2c: i801: Add support for Intel Birch Stream SoC") Link: https://bugzilla.kernel.org/show_bug.cgi?id=220320 Signed-off-by: Chiasheng Lee Cc: # v6.7+ Reviewed-by: Mika Westerberg Reviewed-by: Jarkko Nikula Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250901125943.916522-1-chiasheng.lee@linux.intel.com

i2c: rtl9300: Add missing count byte for SMBus Block Ops

2025-08-19T21:21:03Z

The expected on-wire format of an SMBus Block Write is S Addr Wr [A] Comm [A] Count [A] Data [A] Data [A] ... [A] Data [A] P Everything starting from the Count byte is provided by the I2C subsystem in the array data->block. But the driver was skipping the Count byte (data->block[0]) when sending it to the RTL93xx I2C controller. Only the actual data could be seen on the wire: S Addr Wr [A] Comm [A] Data [A] Data [A] ... [A] Data [A] P This wire format is not SMBus Block Write compatible but matches the format of an I2C Block Write. Simply adding the count byte to the buffer for the I2C controller is enough to fix the transmission. This also affects read because the I2C controller must receive the count byte + $count * data bytes. Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller") Signed-off-by: Sven Eckelmann Cc: # v6.13+ Reviewed-by: Chris Packham Tested-by: Chris Packham Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250810-i2c-rtl9300-multi-byte-v5-4-cd9dca0db722@narfation.org

i2c: rtl9300: Increase timeout for transfer polling

2025-08-19T21:20:02Z

The timeout for transfers was only set to 2ms. Because of this relatively low limit, 12-byte read operations to the frontend MCU of a RTL8239 POE PSE chip cluster was consistently resulting in a timeout. The original OpenWrt downstream driver [1] was not using any timeout limit at all. This is also possible by setting the timeout_us parameter of regmap_read_poll_timeout() to 0. But since the driver currently implements the ETIMEDOUT error, it is more sensible to increase the timeout in such a way that communication with the (quite common) Realtek I2C-connected POE management solution is possible. [1] https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=target/linux/realtek/files-6.12/drivers/i2c/busses/i2c-rtl9300.c;h=c4d973195ef39dc56d6207e665d279745525fcac#l202 Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller") Signed-off-by: Sven Eckelmann Cc: # v6.13+ Reviewed-by: Chris Packham Tested-by: Chris Packham Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250810-i2c-rtl9300-multi-byte-v5-3-cd9dca0db722@narfation.org

i2c: rtl9300: Fix multi-byte I2C write

2025-08-19T21:19:14Z

The RTL93xx I2C controller has 4 32 bit registers to store the bytes for the upcoming I2C transmission. The first byte is stored in the least-significant byte of the first register. And the last byte in the most significant byte of the last register. A map of the transferred bytes to their order in the registers is: reg 0: 0x04_03_02_01 reg 1: 0x08_07_06_05 reg 2: 0x0c_0b_0a_09 reg 3: 0x10_0f_0e_0d The i2c_read() function basically demonstrates how the hardware would pick up bytes from this register set. But the i2c_write() function was just pushing bytes one after another to the least significant byte of a register AFTER shifting the last one to the next more significant byte position. If you would then have tried to send a buffer with numbers 1-11 using i2c_write(), you would have ended up with following register content: reg 0: 0x01_02_03_04 reg 1: 0x05_06_07_08 reg 2: 0x00_09_0a_0b reg 3: 0x00_00_00_00 On the wire, you would then have seen: Sr Addr Wr [A] 04 A 03 A 02 A 01 A 08 A 07 A 06 A 05 A 0b A 0a A 09 A P But the correct data transmission was expected to be Sr Addr Wr [A] 01 A 02 A 03 A 04 A 05 A 06 A 07 A 08 A 09 A 0a A 0b A P Because of this multi-byte ordering problem, only single byte i2c_write() operations were executed correctly (on the wire). By shifting the byte directly to the correct end position in the register, it is possible to avoid this incorrect byte ordering and fix multi-byte transmissions. The second initialization (to 0) of vals was also be dropped because this array is initialized to 0 on the stack by using `= {};`. This makes the fix a lot more readable. Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller") Signed-off-by: Harshal Gohel Cc: # v6.13+ Co-developed-by: Sven Eckelmann Signed-off-by: Sven Eckelmann Reviewed-by: Chris Packham Tested-by: Chris Packham Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250810-i2c-rtl9300-multi-byte-v5-2-cd9dca0db722@narfation.org

i2c: rtl9300: Fix out-of-bounds bug in rtl9300_i2c_smbus_xfer

2025-08-19T21:17:56Z

The data->block[0] variable comes from user. Without proper check, the variable may be very large to cause an out-of-bounds bug. Fix this bug by checking the value of data->block[0] first. 1. commit 39244cc75482 ("i2c: ismt: Fix an out-of-bounds bug in ismt_access()") 2. commit 92fbb6d1296f ("i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()") Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller") Signed-off-by: Alex Guo Cc: # v6.13+ Reviewed-by: Chris Packham Tested-by: Chris Packham Reviewed-by: Wolfram Sang Signed-off-by: Sven Eckelmann Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20250810-i2c-rtl9300-multi-byte-v5-1-cd9dca0db722@narfation.org