From patchwork Wed Jun 2 04:41:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matt Johnston X-Patchwork-Id: 453623 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 350BDC4708F for ; Wed, 2 Jun 2021 04:42:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18C98610E7 for ; Wed, 2 Jun 2021 04:42:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229524AbhFBEny (ORCPT ); Wed, 2 Jun 2021 00:43:54 -0400 Received: from pi.codeconstruct.com.au ([203.29.241.158]:46378 "EHLO codeconstruct.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229658AbhFBEnx (ORCPT ); Wed, 2 Jun 2021 00:43:53 -0400 Received: by codeconstruct.com.au (Postfix, from userid 10001) id 52B4C219AE; Wed, 2 Jun 2021 12:42:02 +0800 (AWST) From: Matt Johnston To: linux-i2c@vger.kernel.org, matt@codeconstruct.com.au Cc: linux-aspeed@lists.ozlabs.org, jk@codeconstruct.com.au Subject: [RFC PATCH 1/3] i2c: core: Allow 255 byte transfers for SMBus 3.x Date: Wed, 2 Jun 2021 12:41:11 +0800 Message-Id: <20210602044113.1581347-2-matt@codeconstruct.com.au> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210602044113.1581347-1-matt@codeconstruct.com.au> References: <20210602044113.1581347-1-matt@codeconstruct.com.au> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org SMBus 3.0 increased the maximum block transfer size from 32 bytes to 255 bytes. We increase the size of struct i2c_smbus_data's block[] member. i2c_smbus_xfer() and i2c_smbus_xfer_emulated() now support 255 byte block operations, other block functions remain limited to 32 bytes for compatibility with existing callers. We allow adapters to indicate support for the larger size with I2C_FUNC_SMBUS_V3_BLOCK. Most emulated drivers should be able to use 255 byte blocks by replacing I2C_SMBUS_BLOCK_MAX with I2C_SMBUS_V3_BLOCK_MAX though some will have hardware limitations that need testing. Signed-off-by: Matt Johnston --- drivers/i2c/i2c-core-smbus.c | 20 +++++++++++++------- include/linux/i2c.h | 13 +++++++++++++ include/uapi/linux/i2c.h | 5 ++++- 3 files changed, 30 insertions(+), 8 deletions(-) diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index d2d32c0fd8c3..8b723d684f54 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -295,7 +295,8 @@ static void i2c_smbus_try_get_dmabuf(struct i2c_msg *msg, u8 init_val) bool is_read = msg->flags & I2C_M_RD; unsigned char *dma_buf; - dma_buf = kzalloc(I2C_SMBUS_BLOCK_MAX + (is_read ? 2 : 3), GFP_KERNEL); + dma_buf = kzalloc(I2C_SMBUS_V3_BLOCK_MAX + (is_read ? 2 : 3), + GFP_KERNEL); if (!dma_buf) return; @@ -321,9 +322,10 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, * initialize most things with sane defaults, to keep the code below * somewhat simpler. */ - unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3]; - unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2]; + unsigned char msgbuf0[I2C_SMBUS_V3_BLOCK_MAX+3]; + unsigned char msgbuf1[I2C_SMBUS_V3_BLOCK_MAX+2]; int nmsgs = read_write == I2C_SMBUS_READ ? 2 : 1; + u16 block_max; u8 partial_pec = 0; int status; struct i2c_msg msg[2] = { @@ -342,6 +344,10 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, bool wants_pec = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK && size != I2C_SMBUS_I2C_BLOCK_DATA); + /* Drivers must opt in to 255 byte max block size */ + block_max = i2c_check_functionality(adapter, I2C_FUNC_SMBUS_V3_BLOCK) + ? I2C_SMBUS_V3_BLOCK_MAX : I2C_SMBUS_BLOCK_MAX; + msgbuf0[0] = command; switch (size) { case I2C_SMBUS_QUICK: @@ -391,7 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, i2c_smbus_try_get_dmabuf(&msg[1], 0); } else { msg[0].len = data->block[0] + 2; - if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) { + if (msg[0].len > block_max + 2) { dev_err(&adapter->dev, "Invalid block write size %d\n", data->block[0]); @@ -405,7 +411,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, case I2C_SMBUS_BLOCK_PROC_CALL: nmsgs = 2; /* Another special case */ read_write = I2C_SMBUS_READ; - if (data->block[0] > I2C_SMBUS_BLOCK_MAX) { + if (data->block[0] > block_max) { dev_err(&adapter->dev, "Invalid block write size %d\n", data->block[0]); @@ -422,7 +428,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, i2c_smbus_try_get_dmabuf(&msg[1], 0); break; case I2C_SMBUS_I2C_BLOCK_DATA: - if (data->block[0] > I2C_SMBUS_BLOCK_MAX) { + if (data->block[0] > block_max) { dev_err(&adapter->dev, "Invalid block %s size %d\n", read_write == I2C_SMBUS_READ ? "read" : "write", data->block[0]); @@ -490,7 +496,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, break; case I2C_SMBUS_BLOCK_DATA: case I2C_SMBUS_BLOCK_PROC_CALL: - if (msg[1].buf[0] > I2C_SMBUS_BLOCK_MAX) { + if (msg[1].buf[0] > block_max) { dev_err(&adapter->dev, "Invalid block size returned: %d\n", msg[1].buf[0]); diff --git a/include/linux/i2c.h b/include/linux/i2c.h index e8f2ac8c9c3d..57170468301e 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -50,6 +50,19 @@ typedef int (*i2c_slave_cb_t)(struct i2c_client *client, struct module; struct property_entry; +/* SMBus 3.0 extends the maximum block read/write size to 255 (from 32). + * The larger size is only supported by some drivers, indicated by + * the I2C_FUNC_SMBUS_V3_BLOCK functionality bit. + */ +#define I2C_SMBUS_V3_BLOCK_MAX 255 /* As specified in SMBus 3.0 standard */ + +/* Note compatibility definition in uapi header with 32 byte block */ +union i2c_smbus_data { + __u8 byte; + __u16 word; + __u8 block[I2C_SMBUS_V3_BLOCK_MAX + 1]; /* block[0] is used for length */ +}; + #if IS_ENABLED(CONFIG_I2C) /* Return the Frequency mode string based on the bus frequency */ const char *i2c_freq_mode_string(u32 bus_freq_hz); diff --git a/include/uapi/linux/i2c.h b/include/uapi/linux/i2c.h index 92326ebde350..7b7d90b50cf0 100644 --- a/include/uapi/linux/i2c.h +++ b/include/uapi/linux/i2c.h @@ -108,6 +108,7 @@ struct i2c_msg { #define I2C_FUNC_SMBUS_READ_I2C_BLOCK 0x04000000 /* I2C-like block xfer */ #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK 0x08000000 /* w/ 1-byte reg. addr. */ #define I2C_FUNC_SMBUS_HOST_NOTIFY 0x10000000 /* SMBus 2.0 or later */ +#define I2C_FUNC_SMBUS_V3_BLOCK 0x20000000 /* Device supports 255 byte block */ #define I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | \ I2C_FUNC_SMBUS_WRITE_BYTE) @@ -137,13 +138,15 @@ struct i2c_msg { /* * Data for SMBus Messages */ -#define I2C_SMBUS_BLOCK_MAX 32 /* As specified in SMBus standard */ +#define I2C_SMBUS_BLOCK_MAX 32 /* As specified in SMBus 2.0 standard */ +#ifndef __KERNEL__ union i2c_smbus_data { __u8 byte; __u16 word; __u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */ /* and one more for user-space compatibility */ }; +#endif /* i2c_smbus_xfer read or write markers */ #define I2C_SMBUS_READ 1