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From:   frank zago <frank@zago.net>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Wolfram Sang <wsa@kernel.org>, Johan Hovold <johan@kernel.org>,
        linux-usb@vger.kernel.org, Lee Jones <lee.jones@linaro.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        linux-gpio@vger.kernel.org, linux-i2c@vger.kernel.org,
        frank zago <frank@zago.net>
Subject: [PATCH v6 1/4] mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode
Date:   Wed, 15 Jun 2022 20:37:44 -0500
Message-Id: <20220616013747.126051-2-frank@zago.net>
In-Reply-To: <20220616013747.126051-1-frank@zago.net>
References: <20220616013747.126051-1-frank@zago.net>
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Precedence: bulk

The CH341 is a multifunction chip, presenting 3 different USB PID. One
of these functions is for I2C/SPI/GPIO. This new set of drivers will
manage I2C and GPIO.

Signed-off-by: frank zago <frank@zago.net>
---
 MAINTAINERS               |  7 +++
 drivers/mfd/Kconfig       | 10 +++++
 drivers/mfd/Makefile      |  1 +
 drivers/mfd/ch341-core.c  | 90 +++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/ch341.h | 18 ++++++++
 5 files changed, 126 insertions(+)
 create mode 100644 drivers/mfd/ch341-core.c
 create mode 100644 include/linux/mfd/ch341.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 43d3d07afccd..628eeaa9bf68 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21475,6 +21475,13 @@ M:	David Härdeman <david@hardeman.nu>
 S:	Maintained
 F:	drivers/media/rc/winbond-cir.c
 
+WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
+M:	Frank Zago <frank@zago.net>
+L:	linux-usb@vger.kernel.org
+S:	Maintained
+F:	drivers/mfd/ch341-core.c
+F:	include/linux/mfd/ch341.h
+
 WINSYSTEMS EBC-C384 WATCHDOG DRIVER
 M:	William Breathitt Gray <vilhelm.gray@gmail.com>
 L:	linux-watchdog@vger.kernel.org
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 3b59456f5545..893acc821a42 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1784,6 +1784,16 @@ config MFD_LOCHNAGAR
 	help
 	  Support for Cirrus Logic Lochnagar audio development board.
 
+config MFD_CH341
+	tristate "WinChipHead CH341 in I2C/SPI/GPIO mode"
+	depends on USB
+	help
+	  If you say yes to this option, support for the CH341 series
+	  of chips, running in I2C/SPI/GPIO mode will be included.
+
+	  This driver can also be built as a module.  If so, the
+	  module will be called ch341-core.
+
 config MFD_ARIZONA
 	select REGMAP
 	select REGMAP_IRQ
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 858cacf659d6..fd615ab3929f 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
 obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
 obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
 obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
+obj-$(CONFIG_MFD_CH341)		+= ch341-core.o
 obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
 obj-$(CONFIG_MFD_ENE_KB3930)	+= ene-kb3930.o
 obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
diff --git a/drivers/mfd/ch341-core.c b/drivers/mfd/ch341-core.c
new file mode 100644
index 000000000000..f08a67dd6074
--- /dev/null
+++ b/drivers/mfd/ch341-core.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Core driver for the CH341A, CH341B and CH341T in I2C/SPI/GPIO
+ * mode. There are cell drivers available for I2C and GPIO. SPI is not
+ * yet supported.
+ *
+ * Copyright 2022, Frank Zago
+ * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
+ * Copyright (c) 2016 Tse Lun Bien
+ * Copyright (c) 2014 Marco Gittler
+ * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
+ */
+
+#include <linux/kernel.h>
+#include <linux/mfd/ch341.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+static const struct mfd_cell ch341_devs[] = {
+	{
+		.name = "ch341-gpio",
+	},
+	{
+		.name = "ch341-i2c",
+	},
+};
+
+static int ch341_usb_probe(struct usb_interface *iface,
+			   const struct usb_device_id *usb_id)
+{
+	struct usb_endpoint_descriptor *bulk_out;
+	struct usb_endpoint_descriptor *bulk_in;
+	struct usb_endpoint_descriptor *intr_in;
+	struct ch341_ddata *ddata;
+	int ret;
+
+	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	ddata->usb_dev = interface_to_usbdev(iface);
+	mutex_init(&ddata->usb_lock);
+
+	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
+					&bulk_out, &intr_in, NULL);
+	if (ret) {
+		dev_err(&iface->dev, "Could not find all endpoints\n");
+		return -ENODEV;
+	}
+
+	ddata->ep_in = bulk_in->bEndpointAddress;
+	ddata->ep_out = bulk_out->bEndpointAddress;
+	ddata->ep_intr = intr_in->bEndpointAddress;
+	ddata->ep_intr_interval = intr_in->bInterval;
+
+	usb_set_intfdata(iface, ddata);
+
+	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
+			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
+	if (ret)
+		return dev_err_probe(&iface->dev, ret,
+				     "Failed to register child devices\n");
+
+	return 0;
+}
+
+static void ch341_usb_disconnect(struct usb_interface *usb_if)
+{
+	mfd_remove_devices(&usb_if->dev);
+}
+
+static const struct usb_device_id ch341_usb_table[] = {
+	{ USB_DEVICE(0x1a86, 0x5512) },
+	{ }
+};
+MODULE_DEVICE_TABLE(usb, ch341_usb_table);
+
+static struct usb_driver ch341_usb_driver = {
+	.name       = "ch341-mfd",
+	.id_table   = ch341_usb_table,
+	.probe      = ch341_usb_probe,
+	.disconnect = ch341_usb_disconnect,
+};
+module_usb_driver(ch341_usb_driver);
+
+MODULE_AUTHOR("Frank Zago <frank@zago.net>");
+MODULE_DESCRIPTION("CH341 USB to I2C/SPI/GPIO adapter");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
new file mode 100644
index 000000000000..44f5da0720bd
--- /dev/null
+++ b/include/linux/mfd/ch341.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Definitions for the CH341 driver */
+
+#include <linux/mutex.h>
+#include <linux/types.h>
+
+struct usb_device;
+struct usb_interface;
+
+struct ch341_ddata {
+	struct usb_device *usb_dev;
+	struct mutex usb_lock;
+
+	int ep_in;
+	int ep_out;
+	int ep_intr;
+	u8 ep_intr_interval;
+};
-- 
2.32.0