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spi: add ch341a usb2spi driver
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Add a driver for the QiHeng Electronics ch341a USB-to-SPI adapter.

This driver is loosely based on the ch341a module from the flashrom project.

Signed-off-by: Johannes Thumshirn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>
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@morbidrsa @broonie
morbidrsa authored and broonie committed Jul 8, 2024
1 parent 0f17a12 commit 8846739
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6 changes: 6 additions & 0 deletions drivers/spi/Kconfig
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Expand Up @@ -277,6 +277,12 @@ config SPI_CADENCE_XSPI
device with a Cadence XSPI controller and want to access the
Flash as an MTD device.

config SPI_CH341
tristate "CH341 USB2SPI adapter"
depends on SPI_MASTER && USB
help
Enables the SPI controller on the CH341a USB to serial chip

config SPI_CLPS711X
tristate "CLPS711X host SPI controller"
depends on ARCH_CLPS711X || COMPILE_TEST
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1 change: 1 addition & 0 deletions drivers/spi/Makefile
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Expand Up @@ -39,6 +39,7 @@ obj-$(CONFIG_SPI_BUTTERFLY) += spi-butterfly.o
obj-$(CONFIG_SPI_CADENCE) += spi-cadence.o
obj-$(CONFIG_SPI_CADENCE_QUADSPI) += spi-cadence-quadspi.o
obj-$(CONFIG_SPI_CADENCE_XSPI) += spi-cadence-xspi.o
obj-$(CONFIG_SPI_CH341) += spi-ch341.o
obj-$(CONFIG_SPI_CLPS711X) += spi-clps711x.o
obj-$(CONFIG_SPI_COLDFIRE_QSPI) += spi-coldfire-qspi.o
obj-$(CONFIG_SPI_CS42L43) += spi-cs42l43.o
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241 changes: 241 additions & 0 deletions drivers/spi/spi-ch341.c
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@@ -0,0 +1,241 @@
// SPDX-License-Identifier: GPL-2.0
//
// QiHeng Electronics ch341a USB-to-SPI adapter driver
//
// Copyright (C) 2024 Johannes Thumshirn <[email protected]>
//
// Based on ch341a_spi.c from the flashrom project.

#include <linux/module.h>
#include <linux/usb.h>
#include <linux/spi/spi.h>

#define CH341_PACKET_LENGTH 32
#define CH341_DEFAULT_TIMEOUT 1000

#define CH341A_CMD_UIO_STREAM 0xab

#define CH341A_CMD_UIO_STM_END 0x20
#define CH341A_CMD_UIO_STM_DIR 0x40
#define CH341A_CMD_UIO_STM_OUT 0x80

#define CH341A_CMD_I2C_STREAM 0xaa
#define CH341A_CMD_I2C_STM_SET 0x60
#define CH341A_CMD_I2C_STM_END 0x00

#define CH341A_CMD_SPI_STREAM 0xa8

#define CH341A_STM_I2C_100K 0x01

struct ch341_spi_dev {
struct spi_controller *ctrl;
struct usb_device *udev;
unsigned int write_pipe;
unsigned int read_pipe;
int rx_len;
void *rx_buf;
u8 *tx_buf;
struct urb *rx_urb;
struct spi_device *spidev;
};

static void ch341_set_cs(struct spi_device *spi, bool is_high)
{
struct ch341_spi_dev *ch341 =
spi_controller_get_devdata(spi->controller);
int err;

memset(ch341->tx_buf, 0, CH341_PACKET_LENGTH);
ch341->tx_buf[0] = CH341A_CMD_UIO_STREAM;
ch341->tx_buf[1] = CH341A_CMD_UIO_STM_OUT | (is_high ? 0x36 : 0x37);

if (is_high) {
ch341->tx_buf[2] = CH341A_CMD_UIO_STM_DIR | 0x3f;
ch341->tx_buf[3] = CH341A_CMD_UIO_STM_END;
} else {
ch341->tx_buf[2] = CH341A_CMD_UIO_STM_END;
}

err = usb_bulk_msg(ch341->udev, ch341->write_pipe, ch341->tx_buf,
(is_high ? 4 : 3), NULL, CH341_DEFAULT_TIMEOUT);
if (err)
dev_err(&spi->dev,
"error sending USB message for setting CS (%d)\n", err);
}

static int ch341_transfer_one(struct spi_controller *host,
struct spi_device *spi,
struct spi_transfer *trans)
{
struct ch341_spi_dev *ch341 =
spi_controller_get_devdata(spi->controller);
int len;
int ret;

len = min(CH341_PACKET_LENGTH, trans->len + 1);

memset(ch341->tx_buf, 0, CH341_PACKET_LENGTH);

ch341->tx_buf[0] = CH341A_CMD_SPI_STREAM;

memcpy(ch341->tx_buf + 1, trans->tx_buf, len);

ret = usb_bulk_msg(ch341->udev, ch341->write_pipe, ch341->tx_buf, len,
NULL, CH341_DEFAULT_TIMEOUT);
if (ret)
return ret;

return usb_bulk_msg(ch341->udev, ch341->read_pipe, trans->rx_buf,
len - 1, NULL, CH341_DEFAULT_TIMEOUT);
}

static void ch341_recv(struct urb *urb)
{
struct ch341_spi_dev *ch341 = urb->context;
struct usb_device *udev = ch341->udev;

switch (urb->status) {
case 0:
/* success */
break;
case -ENOENT:
case -ECONNRESET:
case -EPIPE:
case -ESHUTDOWN:
dev_dbg(&udev->dev, "rx urb terminated with status: %d\n",
urb->status);
return;
default:
dev_dbg(&udev->dev, "rx urb error: %d\n", urb->status);
break;
}
}

static int ch341_config_stream(struct ch341_spi_dev *ch341)
{
memset(ch341->tx_buf, 0, CH341_PACKET_LENGTH);
ch341->tx_buf[0] = CH341A_CMD_I2C_STREAM;
ch341->tx_buf[1] = CH341A_CMD_I2C_STM_SET | CH341A_STM_I2C_100K;
ch341->tx_buf[2] = CH341A_CMD_I2C_STM_END;

return usb_bulk_msg(ch341->udev, ch341->write_pipe, ch341->tx_buf, 3,
NULL, CH341_DEFAULT_TIMEOUT);
}

static int ch341_enable_pins(struct ch341_spi_dev *ch341, bool enable)
{
memset(ch341->tx_buf, 0, CH341_PACKET_LENGTH);
ch341->tx_buf[0] = CH341A_CMD_UIO_STREAM;
ch341->tx_buf[1] = CH341A_CMD_UIO_STM_OUT | 0x37;
ch341->tx_buf[2] = CH341A_CMD_UIO_STM_DIR | (enable ? 0x3f : 0x00);
ch341->tx_buf[3] = CH341A_CMD_UIO_STM_END;

return usb_bulk_msg(ch341->udev, ch341->write_pipe, ch341->tx_buf, 4,
NULL, CH341_DEFAULT_TIMEOUT);
}

static struct spi_board_info chip = {
.modalias = "spi-ch341a",
};

static int ch341_probe(struct usb_interface *intf,
const struct usb_device_id *id)
{
struct usb_device *udev = interface_to_usbdev(intf);
struct usb_endpoint_descriptor *in, *out;
struct ch341_spi_dev *ch341;
struct spi_controller *ctrl;
int ret;

ret = usb_find_common_endpoints(intf->cur_altsetting, &in, &out, NULL,
NULL);
if (ret)
return ret;

ctrl = devm_spi_alloc_master(&udev->dev, sizeof(struct ch341_spi_dev));
if (!ctrl)
return -ENOMEM;

ch341 = spi_controller_get_devdata(ctrl);
ch341->ctrl = ctrl;
ch341->udev = udev;
ch341->write_pipe = usb_sndbulkpipe(udev, usb_endpoint_num(out));
ch341->read_pipe = usb_rcvbulkpipe(udev, usb_endpoint_num(in));

ch341->rx_len = usb_endpoint_maxp(in);
ch341->rx_buf = devm_kzalloc(&udev->dev, ch341->rx_len, GFP_KERNEL);
if (!ch341->rx_buf)
return -ENOMEM;

ch341->rx_urb = usb_alloc_urb(0, GFP_KERNEL);
if (!ch341->rx_urb)
return -ENOMEM;

ch341->tx_buf =
devm_kzalloc(&udev->dev, CH341_PACKET_LENGTH, GFP_KERNEL);
if (!ch341->tx_buf)
return -ENOMEM;

usb_fill_bulk_urb(ch341->rx_urb, udev, ch341->read_pipe, ch341->rx_buf,
ch341->rx_len, ch341_recv, ch341);

ret = usb_submit_urb(ch341->rx_urb, GFP_KERNEL);
if (ret) {
usb_free_urb(ch341->rx_urb);
return -ENOMEM;
}

ctrl->bus_num = -1;
ctrl->mode_bits = SPI_CPHA;
ctrl->transfer_one = ch341_transfer_one;
ctrl->set_cs = ch341_set_cs;
ctrl->auto_runtime_pm = false;

usb_set_intfdata(intf, ch341);

ret = ch341_config_stream(ch341);
if (ret)
return ret;

ret = ch341_enable_pins(ch341, true);
if (ret)
return ret;

ret = spi_register_controller(ctrl);
if (ret)
return ret;

ch341->spidev = spi_new_device(ctrl, &chip);
if (!ch341->spidev)
return -ENOMEM;

return 0;
}

static void ch341_disconnect(struct usb_interface *intf)
{
struct ch341_spi_dev *ch341 = usb_get_intfdata(intf);

spi_unregister_device(ch341->spidev);
spi_unregister_controller(ch341->ctrl);
ch341_enable_pins(ch341, false);
usb_free_urb(ch341->rx_urb);
}

static const struct usb_device_id ch341_id_table[] = {
{ USB_DEVICE(0x1a86, 0x5512) },
{ }
};
MODULE_DEVICE_TABLE(usb, ch341_id_table);

static struct usb_driver ch341a_usb_driver = {
.name = "spi-ch341",
.probe = ch341_probe,
.disconnect = ch341_disconnect,
.id_table = ch341_id_table,
};
module_usb_driver(ch341a_usb_driver);

MODULE_AUTHOR("Johannes Thumshirn <[email protected]>");
MODULE_DESCRIPTION("QiHeng Electronics ch341 USB2SPI");
MODULE_LICENSE("GPL v2");

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