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Subject[PATCH 2/5] USB: serial: f81232: add high baud rate support
Date
The F81232 had 4 clocksource 1.846/18.46/14.77/24MHz and baud rates
can be up to 1.5Mbits with 24MHz.

F81232 Clock registers (106h)

Bit1-0: Clock source selector
00: 1.846MHz.
01: 18.46MHz.
10: 24MHz.
11: 14.77MHz.

Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
---
drivers/usb/serial/f81232.c | 105 +++++++++++++++++++++++++++++++++++++++-----
1 file changed, 94 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
index 46836041c50e..bdd7f337cd5f 100644
--- a/drivers/usb/serial/f81232.c
+++ b/drivers/usb/serial/f81232.c
@@ -28,7 +28,8 @@ static const struct usb_device_id id_table[] = {
MODULE_DEVICE_TABLE(usb, id_table);

/* Maximum baudrate for F81232 */
-#define F81232_MAX_BAUDRATE 115200
+#define F81232_MAX_BAUDRATE 1500000
+#define F81232_DEF_BAUDRATE 9600

/* USB Control EP parameter */
#define F81232_REGISTER_REQUEST 0xa0
@@ -44,18 +45,42 @@ MODULE_DEVICE_TABLE(usb, id_table);
#define LINE_STATUS_REGISTER (0x05 + SERIAL_BASE_ADDRESS)
#define MODEM_STATUS_REGISTER (0x06 + SERIAL_BASE_ADDRESS)

+/*
+ * F81232 Clock registers (106h)
+ *
+ * Bit1-0: Clock source selector
+ * 00: 1.846MHz.
+ * 01: 18.46MHz.
+ * 10: 24MHz.
+ * 11: 14.77MHz.
+ */
+#define F81232_CLK_REGISTER 0x106
+#define F81232_CLK_1_846_MHZ 0
+#define F81232_CLK_18_46_MHZ BIT(0)
+#define F81232_CLK_24_MHZ BIT(1)
+#define F81232_CLK_14_77_MHZ (BIT(1) | BIT(0))
+#define F81232_CLK_MASK GENMASK(1, 0)
+
struct f81232_private {
struct mutex lock;
u8 modem_control;
u8 modem_status;
+ speed_t baud_base;
struct work_struct lsr_work;
struct work_struct interrupt_work;
struct usb_serial_port *port;
};

-static int calc_baud_divisor(speed_t baudrate)
+static u32 const baudrate_table[] = { 115200, 921600, 1152000, 1500000 };
+static u8 const clock_table[] = { F81232_CLK_1_846_MHZ, F81232_CLK_14_77_MHZ,
+ F81232_CLK_18_46_MHZ, F81232_CLK_24_MHZ };
+
+static int calc_baud_divisor(speed_t baudrate, speed_t clockrate)
{
- return DIV_ROUND_CLOSEST(F81232_MAX_BAUDRATE, baudrate);
+ if (!baudrate)
+ return 0;
+
+ return DIV_ROUND_CLOSEST(clockrate, baudrate);
}

static int f81232_get_register(struct usb_serial_port *port, u16 reg, u8 *val)
@@ -129,6 +154,21 @@ static int f81232_set_register(struct usb_serial_port *port, u16 reg, u8 val)
return status;
}

+static int f81232_set_mask_register(struct usb_serial_port *port, u16 reg,
+ u8 mask, u8 val)
+{
+ int status;
+ u8 tmp;
+
+ status = f81232_get_register(port, reg, &tmp);
+ if (status)
+ return status;
+
+ tmp = (tmp & ~mask) | (val & mask);
+
+ return f81232_set_register(port, reg, tmp);
+}
+
static void f81232_read_msr(struct usb_serial_port *port)
{
int status;
@@ -346,13 +386,53 @@ static void f81232_break_ctl(struct tty_struct *tty, int break_state)
*/
}

-static void f81232_set_baudrate(struct usb_serial_port *port, speed_t baudrate)
+static int f81232_find_clk(speed_t baudrate)
+{
+ int idx;
+
+ for (idx = 0; idx < ARRAY_SIZE(baudrate_table); ++idx) {
+ if (baudrate <= baudrate_table[idx] &&
+ baudrate_table[idx] % baudrate == 0)
+ return idx;
+ }
+
+ return -EINVAL;
+}
+
+static void f81232_set_baudrate(struct tty_struct *tty,
+ struct usb_serial_port *port, speed_t baudrate,
+ speed_t old_baudrate)
{
+ struct f81232_private *priv = usb_get_serial_port_data(port);
u8 lcr;
int divisor;
int status = 0;
+ int i;
+ int idx;
+ speed_t baud_list[] = {baudrate, old_baudrate, F81232_DEF_BAUDRATE};
+
+ for (i = 0; i < ARRAY_SIZE(baud_list); ++i) {
+ idx = f81232_find_clk(baud_list[i]);
+ if (idx >= 0) {
+ baudrate = baud_list[i];
+ tty_encode_baud_rate(tty, baudrate, baudrate);
+ break;
+ }
+ }

- divisor = calc_baud_divisor(baudrate);
+ if (idx < 0)
+ return;
+
+ priv->baud_base = baudrate_table[idx];
+ divisor = calc_baud_divisor(baudrate, priv->baud_base);
+
+ status = f81232_set_mask_register(port, F81232_CLK_REGISTER,
+ F81232_CLK_MASK, clock_table[idx]);
+ if (status) {
+ dev_err(&port->dev, "%s failed to set CLK_REG: %d\n",
+ __func__, status);
+ return;
+ }

status = f81232_get_register(port, LINE_CONTROL_REGISTER,
&lcr); /* get LCR */
@@ -442,6 +522,7 @@ static void f81232_set_termios(struct tty_struct *tty,
u8 new_lcr = 0;
int status = 0;
speed_t baudrate;
+ speed_t old_baud;

/* Don't change anything if nothing has changed */
if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
@@ -454,11 +535,12 @@ static void f81232_set_termios(struct tty_struct *tty,

baudrate = tty_get_baud_rate(tty);
if (baudrate > 0) {
- if (baudrate > F81232_MAX_BAUDRATE) {
- baudrate = F81232_MAX_BAUDRATE;
- tty_encode_baud_rate(tty, baudrate, baudrate);
- }
- f81232_set_baudrate(port, baudrate);
+ if (old_termios)
+ old_baud = tty_termios_baud_rate(old_termios);
+ else
+ old_baud = F81232_DEF_BAUDRATE;
+
+ f81232_set_baudrate(tty, port, baudrate, old_baud);
}

if (C_PARENB(tty)) {
@@ -590,6 +672,7 @@ static int f81232_carrier_raised(struct usb_serial_port *port)
static int f81232_get_serial_info(struct usb_serial_port *port,
unsigned long arg)
{
+ struct f81232_private *priv = usb_get_serial_port_data(port);
struct serial_struct ser;

memset(&ser, 0, sizeof(ser));
@@ -597,7 +680,7 @@ static int f81232_get_serial_info(struct usb_serial_port *port,
ser.type = PORT_16550A;
ser.line = port->minor;
ser.port = port->port_number;
- ser.baud_base = F81232_MAX_BAUDRATE;
+ ser.baud_base = priv->baud_base;

if (copy_to_user((void __user *)arg, &ser, sizeof(ser)))
return -EFAULT;
--
2.7.4
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