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SubjectRe: [PATCH] USB: serial: ftdi_sio: add support for FT232H CBUS gpios
On Thu, Aug 08, 2019 at 10:23:48PM +0000, Matthew Michilot wrote:
> Enable support for cbus gpios on FT232H. The cbus configuration is
> stored in one word in the EEPROM at byte-offset 0x1a with the mux

It seems to be stored in two words.

> config for ACBUS5, ACBUS6, ACBUS8 and ACBUS9 (only pins that can be
> configured as I/O mode).
>
> Tested using FT232H by configuring one ACBUS pin at a time.
>
> Review-by: Tim Harvey <tharvey@gateworks.com>

typo: Reviewed-by

> Signed-off-by: Matthew Michilot <matthew.michilot@gmail.com>
> ---
> drivers/usb/serial/ftdi_sio.c | 43 +++++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
> index 4b3a049561f3..c8d35faa8f61 100644
> --- a/drivers/usb/serial/ftdi_sio.c
> +++ b/drivers/usb/serial/ftdi_sio.c
> @@ -2023,6 +2023,46 @@ static int ftdi_read_eeprom(struct usb_serial *serial, void *dst, u16 addr,
> return 0;
> }
>
> +static int ftdi_gpio_init_ft232h(struct usb_serial_port *port)
> +{
> + struct ftdi_private *priv = usb_get_serial_port_data(port);
> + u8 *buf;
> + u16 cbus_config;
> + int ret;
> + int i;
> +
> + buf = kmalloc(2, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + ret = ftdi_read_eeprom(port->serial, buf, 0x1A, 4);

You allocate 2 byte above, but write 4 bytes into buf here.

Please also use lower-case hex notation consistently throughout.

> + if (ret < 0)
> + goto out_free;
> +
> + /*
> + * FT232H CBUS Memory Map
> + *
> + * 0x1A: 8X (upper nibble -> AC5)
> + * 0x1B: X8 (lower nibble -> AC6)
> + * 0x1C: 88 (upper nibble -> AC8 | lower nibble -> AC9)
> + */
> + cbus_config = (((buf[0] & 0xf0) | (buf[1] & 0xf)) << 8 | buf[2]);

Have you verified the order you use here by enabling one gpio at a time
and toggling it? The reason I ask is that the above would give a
mapping of

gpio0 -> AC9
gpio1 -> AC8
gpio2 -> AC6
gpio4 -> AC5

which looks backwards but may be correct.
Also please drop the outer parentheses in the above expression.

> +
> + priv->gc.ngpio = 4;
> + priv->gpio_altfunc = 0xff;
> +
> + for (i = 0; i < priv->gc.ngpio; ++i) {
> + if ((cbus_config & 0xf) == FTDI_FTX_CBUS_MUX_GPIO)
> + priv->gpio_altfunc &= ~BIT(i);
> + cbus_config >>= 4;
> + }
> +
> +out_free:
> + kfree(buf);
> +
> + return ret;
> +}
> +
> static int ftdi_gpio_init_ft232r(struct usb_serial_port *port)
> {
> struct ftdi_private *priv = usb_get_serial_port_data(port);
> @@ -2104,6 +2144,9 @@ static int ftdi_gpio_init(struct usb_serial_port *port)
> case FTX:
> result = ftdi_gpio_init_ftx(port);
> break;
> + case FT232H:
> + result = ftdi_gpio_init_ft232h(port);
> + break;

Please keep the case labels sorted alphabetically.

> default:
> return 0;
> }

Johan

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