From patchwork Thu Jun 16 01:37:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frank Zago X-Patchwork-Id: 582386 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1158C43334 for ; Thu, 16 Jun 2022 01:38:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356452AbiFPBiP (ORCPT ); Wed, 15 Jun 2022 21:38:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357467AbiFPBiM (ORCPT ); Wed, 15 Jun 2022 21:38:12 -0400 Received: from relay12.mail.gandi.net (relay12.mail.gandi.net [IPv6:2001:4b98:dc4:8::232]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E839857B3A; Wed, 15 Jun 2022 18:38:08 -0700 (PDT) Received: (Authenticated sender: frank@zago.net) by mail.gandi.net (Postfix) with ESMTPSA id 35989200006; Thu, 16 Jun 2022 01:38:03 +0000 (UTC) From: frank zago To: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Bartosz Golaszewski , Wolfram Sang , Johan Hovold , linux-usb@vger.kernel.org, Lee Jones , Linus Walleij , linux-gpio@vger.kernel.org, linux-i2c@vger.kernel.org, frank zago Subject: [PATCH v6 3/4] i2c: ch341: add I2C MFD cell driver for the CH341 Date: Wed, 15 Jun 2022 20:37:46 -0500 Message-Id: <20220616013747.126051-4-frank@zago.net> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220616013747.126051-1-frank@zago.net> References: <20220616013747.126051-1-frank@zago.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org The I2C interface can run at 4 different speeds. This driver currently only offer 100kHz. Tested with a variety of I2C sensors, and the IIO subsystem. Signed-off-by: frank zago --- MAINTAINERS | 1 + drivers/i2c/busses/Kconfig | 10 + drivers/i2c/busses/Makefile | 1 + drivers/i2c/busses/i2c-ch341.c | 377 +++++++++++++++++++++++++++++++++ 4 files changed, 389 insertions(+) create mode 100644 drivers/i2c/busses/i2c-ch341.c diff --git a/MAINTAINERS b/MAINTAINERS index 8b93f6192704..837065fd3150 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -21480,6 +21480,7 @@ M: Frank Zago L: linux-usb@vger.kernel.org S: Maintained F: drivers/gpio/gpio-ch341.c +F: drivers/i2c/busses/i2c-ch341.c F: drivers/mfd/ch341-core.c F: include/linux/mfd/ch341.h diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index a1bae59208e3..db9797345ad5 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig @@ -1199,6 +1199,16 @@ config I2C_RCAR comment "External I2C/SMBus adapter drivers" +config I2C_CH341 + tristate "CH341 USB to I2C support" + select MFD_CH341 + help + If you say yes to this option, I2C support will be included for the + WCH CH341, a USB to I2C/SPI/GPIO interface. + + This driver can also be built as a module. If so, the module + will be called i2c-ch341. + config I2C_DIOLAN_U2C tristate "Diolan U2C-12 USB adapter" depends on USB diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile index 479f60e4ee3d..e83ca4a472f2 100644 --- a/drivers/i2c/busses/Makefile +++ b/drivers/i2c/busses/Makefile @@ -127,6 +127,7 @@ obj-$(CONFIG_I2C_XLP9XX) += i2c-xlp9xx.o obj-$(CONFIG_I2C_RCAR) += i2c-rcar.o # External I2C/SMBus adapter drivers +obj-$(CONFIG_I2C_CH341) += i2c-ch341.o obj-$(CONFIG_I2C_DIOLAN_U2C) += i2c-diolan-u2c.o obj-$(CONFIG_I2C_DLN2) += i2c-dln2.o obj-$(CONFIG_I2C_CP2615) += i2c-cp2615.o diff --git a/drivers/i2c/busses/i2c-ch341.c b/drivers/i2c/busses/i2c-ch341.c new file mode 100644 index 000000000000..60c587cca4eb --- /dev/null +++ b/drivers/i2c/busses/i2c-ch341.c @@ -0,0 +1,377 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * I2C cell driver for the CH341A, CH341B and CH341T. + * + * Copyright 2022, Frank Zago + * Copyright (c) 2016 Tse Lun Bien + * Copyright (c) 2014 Marco Gittler + * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org) + */ + +#include +#include +#include +#include +#include +#include +#include + +/* I2C bus speed. Speed selection is not implemented. */ +#define CH341_I2C_20KHZ 0 +#define CH341_I2C_100KHZ 1 +#define CH341_I2C_400KHZ 2 +#define CH341_I2C_750KHZ 3 + +/* I2C chip commands */ +#define CH341_CMD_I2C_STREAM 0xAA +#define CH341_CMD_I2C_STM_END 0x00 + +#define CH341_CMD_I2C_STM_STA 0x74 +#define CH341_CMD_I2C_STM_STO 0x75 +#define CH341_CMD_I2C_STM_OUT 0x80 +#define CH341_CMD_I2C_STM_IN 0xC0 +#define CH341_CMD_I2C_STM_SET 0x60 + +/* + * The maximum request size is 4096 bytes, both for reading and + * writing, split in up to 128 32-byte segments, which includes the + * CH341 commands and the I2C data. + */ +#define SEG_COUNT 128 + +/* + * Limit the transfer size that can be written. 4KiB is the maximum + * size of the whole buffer, but it must include all the command + * delimiters. 3KiB sounds reasonable. + */ +#define MAX_RW_LENGTH 3072 + +struct ch341_i2c { + struct i2c_adapter adapter; + + /* I2C request and response state */ + int idx_out; /* current offset in buf */ + int out_seg; /* current segment */ + u8 i2c_buf[SEG_COUNT * SEG_SIZE]; +}; + +/* + * Special case the no data transfer (SMBUS quick message), since some + * parameters are a bit different than the normal case. + */ +static int no_data_xfer(struct i2c_adapter *adapter, const struct i2c_msg *msg) +{ + struct ch341_i2c *dev = i2c_get_adapdata(adapter); + struct ch341_ddata *ddata = adapter->algo_data; + u8 *out = dev->i2c_buf; + int actual; + int ret; + + out[0] = CH341_CMD_I2C_STREAM; + out[1] = CH341_CMD_I2C_STM_STA; + out[2] = CH341_CMD_I2C_STM_OUT; + out[3] = msg->addr << 1 | (msg->flags & I2C_M_RD); + out[4] = CH341_CMD_I2C_STM_IN; + out[5] = CH341_CMD_I2C_STM_STO; + out[6] = CH341_CMD_I2C_STM_END; + + mutex_lock(&ddata->usb_lock); + + /* Issue the request */ + ret = usb_bulk_msg(ddata->usb_dev, + usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out), + dev->i2c_buf, 7, &actual, DEFAULT_TIMEOUT_MS); + if (ret < 0) { + mutex_unlock(&ddata->usb_lock); + return ret; + } + + ret = usb_bulk_msg(ddata->usb_dev, + usb_rcvbulkpipe(ddata->usb_dev, ddata->ep_in), + dev->i2c_buf, 2, &actual, + DEFAULT_TIMEOUT_MS); + if (ret < 0) { + mutex_unlock(&ddata->usb_lock); + return ret; + } + + mutex_unlock(&ddata->usb_lock); + + if (actual != 2 || dev->i2c_buf[0] & 0x80) + return -ETIMEDOUT; + + return 1; +} + +/* + * Append a write command to the current request. A set of 32-byte + * packets is filled. Each packet starts with STREAM and finishes with + * END, and contains an OUT field, leaving up to 29 bytes of data. The + * first packet must also include a START and the device address. + */ +static int append_write(struct ch341_i2c *dev, const struct i2c_msg *msg) +{ + bool start_done = false; + u8 *out = dev->i2c_buf; + int len; + u8 *p; + + len = msg->len; + p = msg->buf; + + while (len) { + int to_write; + int avail; + + if (dev->idx_out % SEG_SIZE) { + /* Finish current packet, and advance to the next one */ + out[dev->idx_out++] = CH341_CMD_I2C_STM_END; + dev->out_seg++; + dev->idx_out = dev->out_seg * SEG_SIZE; + + if (dev->out_seg == SEG_COUNT) + return -E2BIG; + } + + out[dev->idx_out++] = CH341_CMD_I2C_STREAM; + + /* account for stream start and end */ + avail = SEG_SIZE - 3; + + if (!start_done) { + /* Each message has a start */ + out[dev->idx_out++] = CH341_CMD_I2C_STM_STA; + + avail -= 2; /* room for STA and device address */ + } + + to_write = min_t(int, len, avail); + + if (!start_done) { + out[dev->idx_out++] = CH341_CMD_I2C_STM_OUT | (to_write + 1); + out[dev->idx_out++] = msg->addr << 1; + + start_done = true; + } else { + out[dev->idx_out++] = CH341_CMD_I2C_STM_OUT | to_write; + } + + memcpy(&out[dev->idx_out], p, to_write); + dev->idx_out += to_write; + len -= to_write; + p += to_write; + } + + return 0; +} + +/* + * Append a read command to the request. It usually follows a write + * command. When that happens, the driver will attempt to concat the + * read command into the same packet. Each read command, of up to 32 + * bytes, must be written to a new packet. It is not possible to + * concat them. + */ +static int append_read(struct ch341_i2c *dev, const struct i2c_msg *msg) +{ + bool start_done = false; + u8 *out = dev->i2c_buf; + int len; + + len = msg->len; + + while (len) { + int to_read; + + if (dev->idx_out % SEG_SIZE) { + if (!start_done && + (dev->idx_out % SEG_SIZE) < (SEG_SIZE - 7)) { + /* There's enough left for a read */ + } else { + /* Finish current packet, and advance to the next one */ + out[dev->idx_out++] = CH341_CMD_I2C_STM_END; + dev->out_seg++; + dev->idx_out = dev->out_seg * SEG_SIZE; + + if (dev->out_seg == SEG_COUNT) + return -E2BIG; + + out[dev->idx_out++] = CH341_CMD_I2C_STREAM; + } + } else { + out[dev->idx_out++] = CH341_CMD_I2C_STREAM; + } + + if (!start_done) { + /* Each message has a start */ + out[dev->idx_out++] = CH341_CMD_I2C_STM_STA; + out[dev->idx_out++] = CH341_CMD_I2C_STM_OUT | 1; + out[dev->idx_out++] = msg->addr << 1 | 1; + + start_done = true; + } + + /* Apparently the last command must be an STM_IN to + * read the last byte. Without it, the adapter gets + * lost. + */ + to_read = min_t(int, len, 32); + len -= to_read; + if (len == 0) { + if (to_read > 1) + out[dev->idx_out++] = CH341_CMD_I2C_STM_IN | (to_read - 1); + out[dev->idx_out++] = CH341_CMD_I2C_STM_IN; + } else { + out[dev->idx_out++] = CH341_CMD_I2C_STM_IN | to_read; + } + } + + return 0; +} + +static int ch341_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) +{ + struct ch341_i2c *dev = i2c_get_adapdata(adapter); + struct ch341_ddata *ddata = adapter->algo_data; + u8 *out = dev->i2c_buf; + int actual; + int ret; + int i; + + /* Special case */ + if (num == 1 && msgs[0].len == 0) + return no_data_xfer(adapter, &msgs[0]); + + /* Prepare the request */ + dev->idx_out = 0; + dev->out_seg = 0; + + for (i = 0; i != num; i++) { + if (msgs[i].flags & I2C_M_RD) + ret = append_read(dev, &msgs[i]); + else + ret = append_write(dev, &msgs[i]); + + if (ret) + return ret; + } + + /* Finish the last packet */ + if (SEG_SIZE - (dev->idx_out % SEG_SIZE) < 2) { + out[dev->idx_out++] = CH341_CMD_I2C_STM_END; + + dev->out_seg++; + if (dev->out_seg == SEG_COUNT) + return -E2BIG; + + dev->idx_out = dev->out_seg * SEG_SIZE; + + out[dev->idx_out++] = CH341_CMD_I2C_STREAM; + } + + out[dev->idx_out++] = CH341_CMD_I2C_STM_STO; + out[dev->idx_out++] = CH341_CMD_I2C_STM_END; + + mutex_lock(&ddata->usb_lock); + + /* Issue the request */ + ret = usb_bulk_msg(ddata->usb_dev, + usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out), + dev->i2c_buf, dev->idx_out, &actual, DEFAULT_TIMEOUT_MS); + if (ret < 0) { + mutex_unlock(&ddata->usb_lock); + return ret; + } + + for (i = 0; i != num; i++) { + if (!(msgs[i].flags & I2C_M_RD)) + continue; + + ret = usb_bulk_msg(ddata->usb_dev, + usb_rcvbulkpipe(ddata->usb_dev, ddata->ep_in), + dev->i2c_buf, msgs[i].len, &actual, + DEFAULT_TIMEOUT_MS); + + if (ret) { + mutex_unlock(&ddata->usb_lock); + return ret; + } + + if (actual != msgs[i].len) { + mutex_unlock(&ddata->usb_lock); + return -EIO; + } + + memcpy(msgs[i].buf, dev->i2c_buf, actual); + } + + mutex_unlock(&ddata->usb_lock); + + return num; +} + +static u32 ch341_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm ch341_i2c_algorithm = { + .master_xfer = ch341_i2c_xfer, + .functionality = ch341_i2c_func, +}; + +static const struct i2c_adapter_quirks ch341_i2c_quirks = { + .max_read_len = MAX_RW_LENGTH, + .max_write_len = MAX_RW_LENGTH, +}; + +static int ch341_i2c_probe(struct platform_device *pdev) +{ + struct ch341_ddata *ddata = dev_get_drvdata(pdev->dev.parent); + struct ch341_i2c *ch341_i2c; + int actual; + int ret; + + ch341_i2c = devm_kzalloc(&pdev->dev, sizeof(*ch341_i2c), GFP_KERNEL); + if (ch341_i2c == NULL) + return -ENOMEM; + + ch341_i2c->adapter.owner = THIS_MODULE; + ch341_i2c->adapter.class = I2C_CLASS_HWMON; + ch341_i2c->adapter.algo = &ch341_i2c_algorithm; + ch341_i2c->adapter.algo_data = ddata; + ch341_i2c->adapter.quirks = &ch341_i2c_quirks; + ch341_i2c->adapter.dev.parent = &pdev->dev; + snprintf(ch341_i2c->adapter.name, sizeof(ch341_i2c->adapter.name), + "CH341 I2C USB bus %03d device %03d", + ddata->usb_dev->bus->busnum, ddata->usb_dev->devnum); + + i2c_set_adapdata(&ch341_i2c->adapter, ch341_i2c); + platform_set_drvdata(pdev, ch341_i2c); + + /* Set ch341 i2c speed */ + ch341_i2c->i2c_buf[0] = CH341_CMD_I2C_STREAM; + ch341_i2c->i2c_buf[1] = CH341_CMD_I2C_STM_SET | CH341_I2C_100KHZ; + ch341_i2c->i2c_buf[2] = CH341_CMD_I2C_STM_END; + mutex_lock(&ddata->usb_lock); + ret = usb_bulk_msg(ddata->usb_dev, + usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out), + ch341_i2c->i2c_buf, 3, &actual, DEFAULT_TIMEOUT_MS); + mutex_unlock(&ddata->usb_lock); + + if (ret < 0) + return dev_err_probe(&pdev->dev, ret, "Cannot set I2C speed\n"); + + return devm_i2c_add_adapter(&pdev->dev, &ch341_i2c->adapter); +} + +static struct platform_driver ch341_i2c_driver = { + .driver.name = "ch341-i2c", + .probe = ch341_i2c_probe, +}; +module_platform_driver(ch341_i2c_driver); + +MODULE_AUTHOR("Frank Zago "); +MODULE_DESCRIPTION("CH341 USB to I2C"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:ch341-i2c");