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|
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
* Copyright 2007, Werner Cornelius <werner@cornelius-consult.de>
* Copyright 2009, Boris Hajduk <boris@hajduk.org>
*
* ch341.c implements a serial port driver for the Winchiphead CH341.
*
* The CH341 device can be used to implement an RS232 asynchronous
* serial port, an IEEE-1284 parallel printer port or a memory-like
* interface. In all cases the CH341 supports an I2C interface as well.
* This driver only supports the asynchronous serial interface.
*/
#include <linux/kernel.h>
#include <linux/tty.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/serial.h>
#include <asm/unaligned.h>
#define DEFAULT_BAUD_RATE 9600
#define DEFAULT_TIMEOUT 1000
/* flags for IO-Bits */
#define CH341_BIT_RTS (1 << 6)
#define CH341_BIT_DTR (1 << 5)
/******************************/
/* interrupt pipe definitions */
/******************************/
/* always 4 interrupt bytes */
/* first irq byte normally 0x08 */
/* second irq byte base 0x7d + below */
/* third irq byte base 0x94 + below */
/* fourth irq byte normally 0xee */
/* second interrupt byte */
#define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
/* status returned in third interrupt answer byte, inverted in data
from irq */
#define CH341_BIT_CTS 0x01
#define CH341_BIT_DSR 0x02
#define CH341_BIT_RI 0x04
#define CH341_BIT_DCD 0x08
#define CH341_BITS_MODEM_STAT 0x0f /* all bits */
/* Break support - the information used to implement this was gleaned from
* the Net/FreeBSD uchcom.c driver by Takanori Watanabe. Domo arigato.
*/
#define CH341_REQ_READ_VERSION 0x5F
#define CH341_REQ_WRITE_REG 0x9A
#define CH341_REQ_READ_REG 0x95
#define CH341_REQ_SERIAL_INIT 0xA1
#define CH341_REQ_MODEM_CTRL 0xA4
#define CH341_REG_BREAK 0x05
#define CH341_REG_LCR 0x18
#define CH341_NBREAK_BITS 0x01
#define CH341_LCR_ENABLE_RX 0x80
#define CH341_LCR_ENABLE_TX 0x40
#define CH341_LCR_MARK_SPACE 0x20
#define CH341_LCR_PAR_EVEN 0x10
#define CH341_LCR_ENABLE_PAR 0x08
#define CH341_LCR_STOP_BITS_2 0x04
#define CH341_LCR_CS8 0x03
#define CH341_LCR_CS7 0x02
#define CH341_LCR_CS6 0x01
#define CH341_LCR_CS5 0x00
static const struct usb_device_id id_table[] = {
{ USB_DEVICE(0x4348, 0x5523) },
{ USB_DEVICE(0x1a86, 0x7523) },
{ USB_DEVICE(0x1a86, 0x5523) },
{ },
};
MODULE_DEVICE_TABLE(usb, id_table);
struct ch341_private {
spinlock_t lock; /* access lock */
unsigned baud_rate; /* set baud rate */
u8 mcr;
u8 msr;
u8 lcr;
};
static void ch341_set_termios(struct tty_struct *tty,
struct usb_serial_port *port,
struct ktermios *old_termios);
static int ch341_control_out(struct usb_device *dev, u8 request,
u16 value, u16 index)
{
int r;
dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
request, value, index);
r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
value, index, NULL, 0, DEFAULT_TIMEOUT);
if (r < 0)
dev_err(&dev->dev, "failed to send control message: %d\n", r);
return r;
}
static int ch341_control_in(struct usb_device *dev,
u8 request, u16 value, u16 index,
char *buf, unsigned bufsize)
{
int r;
dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
request, value, index, bufsize);
r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
value, index, buf, bufsize, DEFAULT_TIMEOUT);
if (r < (int)bufsize) {
if (r >= 0) {
dev_err(&dev->dev,
"short control message received (%d < %u)\n",
r, bufsize);
r = -EIO;
}
dev_err(&dev->dev, "failed to receive control message: %d\n",
r);
return r;
}
return 0;
}
#define CH341_CLKRATE 48000000
#define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
#define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
static const speed_t ch341_min_rates[] = {
CH341_MIN_RATE(0),
CH341_MIN_RATE(1),
CH341_MIN_RATE(2),
CH341_MIN_RATE(3),
};
/*
* The device line speed is given by the following equation:
*
* baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
*
* 0 <= ps <= 3,
* 0 <= fact <= 1,
* 2 <= div <= 256 if fact = 0, or
* 9 <= div <= 256 if fact = 1
*/
static int ch341_get_divisor(speed_t speed)
{
unsigned int fact, div, clk_div;
int ps;
/*
* Clamp to supported range, this makes the (ps < 0) and (div < 2)
* sanity checks below redundant.
*/
speed = clamp(speed, 46U, 3000000U);
/*
* Start with highest possible base clock (fact = 1) that will give a
* divisor strictly less than 512.
*/
fact = 1;
for (ps = 3; ps >= 0; ps--) {
if (speed > ch341_min_rates[ps])
break;
}
if (ps < 0)
return -EINVAL;
/* Determine corresponding divisor, rounding down. */
clk_div = CH341_CLK_DIV(ps, fact);
div = CH341_CLKRATE / (clk_div * speed);
/* Halve base clock (fact = 0) if required. */
if (div < 9 || div > 255) {
div /= 2;
clk_div *= 2;
fact = 0;
}
if (div < 2)
return -EINVAL;
/*
* Pick next divisor if resulting rate is closer to the requested one,
* scale up to avoid rounding errors on low rates.
*/
if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
div++;
/*
* Prefer lower base clock (fact = 0) if even divisor.
*
* Note that this makes the receiver more tolerant to errors.
*/
if (fact == 1 && div % 2 == 0) {
div /= 2;
fact = 0;
}
return (0x100 - div) << 8 | fact << 2 | ps;
}
static int ch341_set_baudrate_lcr(struct usb_device *dev,
struct ch341_private *priv, u8 lcr)
{
int val;
int r;
if (!priv->baud_rate)
return -EINVAL;
val = ch341_get_divisor(priv->baud_rate);
if (val < 0)
return -EINVAL;
/*
* CH341A buffers data until a full endpoint-size packet (32 bytes)
* has been received unless bit 7 is set.
*/
val |= BIT(7);
r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, val);
if (r)
return r;
r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr);
if (r)
return r;
return r;
}
static int ch341_set_handshake(struct usb_device *dev, u8 control)
{
return ch341_control_out(dev
|