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drivers/usb: Add option for baudrate of FT232H UART

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The maximum supported rate is 12MHz. Only tested with 4MHz though,
since I couldn't set anything higher on my Linux receiver. But that
works fine with another FT*232H as receiver, whoosh.

Change-Id: Ie39aa0170882ff5b4512f0349f6f86d3f0b86421
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/17477
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
This commit is contained in:
Nico Huber
2016-11-18 20:11:43 +01:00
parent 378d79eb30
commit c868fd16a7
2 changed files with 41 additions and 2 deletions
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31
src/drivers/usb/gadget.c
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@@ -226,11 +226,38 @@ small_write:
#define FTDI_SIO_SET_DATA_REQUEST 0x04
#define FTDI_SIO_SET_BITMODE_REQUEST 0x0b
/* Simplified divisor selection for 12MHz base clock only */
static void ft232h_baud(u16 *const value, u16 *const index, u32 baud)
{
static const u32 fraction_map[8] = { 0, 3, 2, 4, 1, 5, 6, 7 };
/* divisor must fit into 14 bits */
if (baud < 733)
baud = 733;
/* divisor is given as a fraction of 8 */
const u32 div8 = ((12 * 1000 * 1000) * 8) / baud;
/* upper 3 bits fractional part, lower 14 bits integer */
u32 div = fraction_map[div8 & 7] << 14 | div8 / 8;
/* special case for 12MHz */
if (div == 1)
div = 0;
/* special case for 8MHz */
else if (div == (fraction_map[4] << 14 | 1))
div = 1;
*value = div; /* divisor lower 16 bits */
*index = (div >> 8) & 0x0100; /* divisor bit 16 */
*index |= 0x0200; /* select 120MHz / 10 */
}
static int probe_for_ftdi(struct ehci_dbg_port *ehci_debug, struct dbgp_pipe *pipe)
{
int ret;
u8 devnum = 0;
u8 uart_if = 1; /* FTDI_INTERFACE_A 1 */
u16 baud_value, baud_index;
/* Move the device to 127 if it isn't already there */
ret = dbgp_control_msg(ehci_debug, devnum,
@@ -260,10 +287,12 @@ static int probe_for_ftdi(struct ehci_dbg_port *ehci_debug, struct dbgp_pipe *pi
dprintk(BIOS_INFO, "FTDI SET_BITMODE failed.\n");
return -3;
}
ft232h_baud(&baud_value, &baud_index,
CONFIG_USBDEBUG_DONGLE_FTDI_FT232H_BAUD);
ret = dbgp_control_msg(ehci_debug, devnum,
USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
FTDI_SIO_SET_BAUDRATE_REQUEST,
0xc068, 0x0200 | uart_if, NULL, 0);
baud_value, baud_index | uart_if, NULL, 0);
if (ret < 0) {
dprintk(BIOS_INFO, "FTDI SET_BAUDRATE failed.\n");
return -3;