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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b06e61119bsm62450855ad.64.2026.03.19.11.18.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 19 Mar 2026 11:18:18 -0700 (PDT) Sender: Guenter Roeck Message-ID: Date: Thu, 19 Mar 2026 11:18:16 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 11/12] hwmon: spd5118: Add I3C support To: Akhil R Cc: Frank.Li@nxp.com, acpica-devel@lists.linux.dev, alexandre.belloni@bootlin.com, conor+dt@kernel.org, devicetree@vger.kernel.org, ebiggers@kernel.org, fredrik.markstrom@est.tech, jonathanh@nvidia.com, krzk+dt@kernel.org, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-i3c@lists.infradead.org, linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org, miquel.raynal@bootlin.com, p.zabel@pengutronix.de, rafael@kernel.org, robert.moore@intel.com, robh@kernel.org, smangipudi@nvidia.com, thierry.reding@kernel.org References: <7cc8ab1f-6c9a-4e3f-a1bc-266e020d8179@roeck-us.net> <20260319175533.19480-1-akhilrajeev@nvidia.com> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAmgrMyQFCSbODQkACgkQyx8mb86fmYGcWRAA oRwrk7V8fULqnGGpBIjp7pvR187Yzx+lhMGUHuM5H56TFEqeVwCMLWB2x1YRolYbY4MEFlQg VUFcfeW0OknSr1s6wtrtQm0gdkolM8OcCL9ptTHOg1mmXa4YpW8QJiL0AVtbpE9BroeWGl9v 2TGILPm9mVp+GmMQgkNeCS7Jonq5f5pDUGumAMguWzMFEg+Imt9wr2YA7aGen7KPSqJeQPpj onPKhu7O/KJKkuC50ylxizHzmGx+IUSmOZxN950pZUFvVZH9CwhAAl+NYUtcF5ry/uSYG2U7 DCvpzqOryJRemKN63qt1bjF6cltsXwxjKOw6CvdjJYA3n6xCWLuJ6yk6CAy1Ukh545NhgBAs rGGVkl6TUBi0ixL3EF3RWLa9IMDcHN32r7OBhw6vbul8HqyTFZWY2ksTvlTl+qG3zV6AJuzT WdXmbcKN+TdhO5XlxVlbZoCm7ViBj1+PvIFQZCnLAhqSd/DJlhaq8fFXx1dCUPgQDcD+wo65 qulV/NijfU8bzFfEPgYP/3LP+BSAyFs33y/mdP8kbMxSCjnLEhimQMrSSo/To1Gxp5C97fw5 3m1CaMILGKCmfI1B8iA8zd8ib7t1Rg0qCwcAnvsM36SkrID32GfFbv873bNskJCHAISK3Xkz qo7IYZmjk/IJGbsiGzxUhvicwkgKE9r7a1rOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAmgrMyQFCSbODQkACgkQyx8mb86fmYHlgg/9 H5JeDmB4jsreE9Bn621wZk7NMzxy9STxiVKSh8Mq4pb+IDu1RU2iLyetCY1TiJlcxnE362kj njrfAdqyPteHM+LU59NtEbGwrfcXdQoh4XdMuPA5ADetPLma3YiRa3VsVkLwpnR7ilgwQw6u dycEaOxQ7LUXCs0JaGVVP25Z2hMkHBwx6BlW6EZLNgzGI2rswSZ7SKcsBd1IRHVf0miwIFYy j/UEfAFNW+tbtKPNn3xZTLs3quQN7GdYLh+J0XxITpBZaFOpwEKV+VS36pSLnNl0T5wm0E/y scPJ0OVY7ly5Vm1nnoH4licaU5Y1nSkFR/j2douI5P7Cj687WuNMC6CcFd6j72kRfxklOqXw zvy+2NEcXyziiLXp84130yxAKXfluax9sZhhrhKT6VrD45S6N3HxJpXQ/RY/EX35neH2/F7B RgSloce2+zWfpELyS1qRkCUTt1tlGV2p+y2BPfXzrHn2vxvbhEn1QpQ6t+85FKN8YEhJEygJ F0WaMvQMNrk9UAUziVcUkLU52NS9SXqpVg8vgrO0JKx97IXFPcNh0DWsSj/0Y8HO/RDkGXYn FDMj7fZSPKyPQPmEHg+W/KzxSSfdgWIHF2QaQ0b2q1wOSec4Rti52ohmNSY+KNIW/zODhugJ np3900V20aS7eD9K8GTU0TGC1pyz6IVJwIE= In-Reply-To: <20260319175533.19480-1-akhilrajeev@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/19/26 10:55, Akhil R wrote: > On Thu, 19 Mar 2026 07:34:18 -0700, Guenter Roeck wrote: >> On 3/18/26 21:35, Akhil R wrote: >>> On Wed, 18 Mar 2026 11:53:49 -0700, Guenter Roeck wrote: >>>> On 3/18/26 10:27, Akhil R wrote: >>>>> Add a regmap config and a probe function to support for I3C based >>>>> communication to SPD5118 devices. >>>>> >>>>> On an I3C bus, SPD5118 are enumerated via SETAASA and always require an >>>>> ACPI or device tree entry. The device matching is hence through the OF >>>>> match tables only and do not need an I3C class match table. The device >>>>> identity is verified in the type registers before proceeding to the >>>>> common probe function. >>>>> >>>>> Signed-off-by: Akhil R >>>>> --- >>>>> drivers/hwmon/Kconfig | 7 +++-- >>>>> drivers/hwmon/spd5118.c | 66 ++++++++++++++++++++++++++++++++++++++++- >>>>> 2 files changed, 70 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig >>>>> index 8af80e17d25e..23604c05ad22 100644 >>>>> --- a/drivers/hwmon/Kconfig >>>>> +++ b/drivers/hwmon/Kconfig >>>>> @@ -2300,10 +2300,13 @@ config SENSORS_SPD5118 >>>>> tristate "SPD5118 Compliant Temperature Sensors" >>>>> depends on I2C >>>>> select REGMAP_I2C >>>> >>>> I also had >>>> depends on I3C || I3C=n >>>> in my version at >>>> >>>> https://patchwork.kernel.org/project/linux-hwmon/patch/20250419161356.2528986-6-linux@roeck-us.net/ >>>> >>>> which I guess matches the more recent "depends on I3C_OR_I2C". >>> >>> Ack. Will update. >>> >>>> >>>>> + select REGMAP_I3C if I3C >>>>> help >>>>> If you say yes here you get support for SPD5118 (JEDEC JESD300) >>>>> - compliant temperature sensors. Such sensors are found on DDR5 memory >>>>> - modules. >>>>> + compliant temperature sensors using I2C or I3C bus interface. >>>>> + Such sensors are found on DDR5 memory modules. >>>>> + >>>>> + This driver supports both I2C and I3C interfaces. >>>>> >>>>> This driver can also be built as a module. If so, the module >>>>> will be called spd5118. >>>>> diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c >>>>> index 5da44571b6a0..d70123e10616 100644 >>>>> --- a/drivers/hwmon/spd5118.c >>>>> +++ b/drivers/hwmon/spd5118.c >>>>> @@ -18,6 +18,7 @@ >>>>> #include >>>>> #include >>>>> #include >>>>> +#include >>>>> #include >>>>> #include >>>>> #include >>>>> @@ -482,6 +483,25 @@ static const struct regmap_config spd5118_regmap16_config = { >>>>> .cache_type = REGCACHE_MAPLE, >>>>> }; >>>>> >>>>> +/* >>>>> + * I3C uses 2-byte register addressing - >>>>> + * Byte 1: MemReg | BlkAddr[0] | Address[5:0] >>>>> + * Byte 2: 0000 | BlkAddr[4:1] >>>>> + * >>>>> + * The low byte carries the register/NVM address and the high byte carries the >>>>> + * upper block address bits, so little-endian format is required. No range >>>>> + * config is needed since I3C does not use MR11 page switching. >>>>> + */ >>>>> +static const struct regmap_config spd5118_regmap_i3c_config = { >>>>> + .reg_bits = 16, >>>>> + .val_bits = 8, >>>>> + .max_register = 0x7ff, >>>>> + .reg_format_endian = REGMAP_ENDIAN_LITTLE, >>>> >>>> Should this be added to spd5118_regmap16_config instead, or is there reason >>>> to assume that I2C 16-bit addressing differs from I3C addressing ? >>> >>> I did not see any difference for I2C in the specification, but I assumed the >>> existing format would have been working and I thought not to change them. >>> Changing the I2C format would also require a change in the is_16bit nvmem_read >>> formula. >>> >>>> >>>>> + .writeable_reg = spd5118_writeable_reg, >>>>> + .volatile_reg = spd5118_volatile_reg, >>>>> + .cache_type = REGCACHE_MAPLE, >>>>> +}; >>>>> + >>>>> static int spd5118_suspend(struct device *dev) >>>>> { >>>>> struct spd5118_data *data = dev_get_drvdata(dev); >>>>> @@ -770,7 +790,51 @@ static struct i2c_driver spd5118_i2c_driver = { >>>>> .address_list = IS_ENABLED(CONFIG_SENSORS_SPD5118_DETECT) ? normal_i2c : NULL, >>>>> }; >>>>> >>>>> -module_i2c_driver(spd5118_i2c_driver); >>>>> +/* I3C */ >>>>> + >>>>> +static int spd5118_i3c_probe(struct i3c_device *i3cdev) >>>>> +{ >>>>> + struct device *dev = i3cdev_to_dev(i3cdev); >>>>> + struct regmap *regmap; >>>>> + unsigned int regval; >>>>> + int err; >>>>> + >>>>> + regmap = devm_regmap_init_i3c(i3cdev, &spd5118_regmap_i3c_config); >>>>> + if (IS_ERR(regmap)) >>>>> + return dev_err_probe(dev, PTR_ERR(regmap), "regmap init failed\n"); >>>>> + >>>>> + /* Verify this is a SPD5118 device */ >>>>> + err = regmap_read(regmap, SPD5118_REG_TYPE, ®val); >>>>> + if (err) >>>>> + return err; >>>>> + >>>>> + if (regval != 0x51) { >>>>> + dev_err(dev, "unexpected device type 0x%02x, expected 0x51\n", regval); >>>>> + return -ENODEV; >>>>> + } >>>>> + >>>>> + err = regmap_read(regmap, SPD5118_REG_TYPE + 1, ®val); >>>>> + if (err) >>>>> + return err; >>>>> + >>>>> + if (regval != 0x18) { >>>>> + dev_err(dev, "unexpected device type 0x%02x, expected 0x18\n", regval); >>>>> + return -ENODEV; >>>>> + } >>>>> + >>>> >>>> I don't think this should dump error messages. Also, it might be desirable >>>> to use a single regmap operation to read both values. >>> >>> Ack. Will use regmap_bulk_read() and will remove the error dump. >>> >>>> >>>>> + return spd5118_common_probe(dev, regmap, false); >>>> >>>> Why is_16bit=false ? >>> >>> We don't need the encoding formula for the nvmem address with I3C. Since it >>> uses little-endian, (page * 0x100 + SPD5118_EEPROM_BASE) translates to the >>> correct address. Or did I overlook something? >>> >> >> Testing of the 16-bit code was limited: I had to set the SPD on a system >> manually to 16-bit mode to get it working, and that only worked until the system >> was reset. Its whole point was to prepare for I3C mode. If that fails, the entire >> 16-bit code in the driver is potentially wrong and should be pulled out before >> adding I3C code. It can be added back later if/when a system actually utilizing >> it is found. > > Thanks for letting me know. I will add a patch to remove the I2C 16-bit sections in > the next revision as a prerequistie to this patch. Hope that sounds good. > Please do. Thanks, Guenter > Best Regards, > Akhil