2021-05-28 20:40:54

by Stefan Agner

Subject: [PATCH] USB: serial: cp210x: Fix alternate function for CP2102N QFN20

The QFN20 part has a different GPIO/port function assignment. The
configuration struct bit field ordered as TX/RX/RS485/WAKEUP/CLK
which exactly matches GPIO0-3 for QFN24/28. However, QFN20 has a
different GPIO to primary function assignment.

Special case QFN20 to follow to properly detect which GPIOs are
available.

Signed-off-by: Stefan Agner <[email protected]>
---
Tested on a custom PCB with a CP2102N QFP20 device. I noticed the bug after
configuring GPIO.2/3 to be TX/RX LED.

--
Stefan

drivers/usb/serial/cp210x.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index ee595d1bea0a..c9f8ebd34122 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -537,6 +537,12 @@ struct cp210x_single_port_config {
#define CP210X_2NCONFIG_GPIO_RSTLATCH_IDX 587
#define CP210X_2NCONFIG_GPIO_CONTROL_IDX 600

+/* CP2102N QFN20 port configuration values */
+#define CP2102N_QFN20_GPIO2_TXLED_MODE BIT(2)
+#define CP2102N_QFN20_GPIO3_RXLED_MODE BIT(3)
+#define CP2102N_QFN20_GPIO1_RS485_MODE BIT(4)
+#define CP2102N_QFN20_GPIO0_CLK_MODE BIT(6)
+
/* CP210X_VENDOR_SPECIFIC, CP210X_WRITE_LATCH call writes these 0x2 bytes. */
struct cp210x_gpio_write {
u8 mask;
@@ -1733,7 +1739,19 @@ static int cp2102n_gpioconf_init(struct usb_serial *serial)
priv->gpio_pushpull = (gpio_pushpull >> 3) & 0x0f;

/* 0 indicates GPIO mode, 1 is alternate function */
- priv->gpio_altfunc = (gpio_ctrl >> 2) & 0x0f;
+ if (priv->partnum == CP210X_PARTNUM_CP2102N_QFN20) {
+ /* QFN20 is special... */
+ if (gpio_ctrl & CP2102N_QFN20_GPIO0_CLK_MODE) /* GPIO 0 */
+ priv->gpio_altfunc |= BIT(0);
+ if (gpio_ctrl & CP2102N_QFN20_GPIO1_RS485_MODE) /* GPIO 1 */
+ priv->gpio_altfunc |= BIT(1);
+ if (gpio_ctrl & CP2102N_QFN20_GPIO2_TXLED_MODE) /* GPIO 2 */
+ priv->gpio_altfunc |= BIT(2);
+ if (gpio_ctrl & CP2102N_QFN20_GPIO3_RXLED_MODE) /* GPIO 3 */
+ priv->gpio_altfunc |= BIT(3);
+ } else {
+ priv->gpio_altfunc = (gpio_ctrl >> 2) & 0x0f;
+ }

if (priv->partnum == CP210X_PARTNUM_CP2102N_QFN28) {
/*
--
2.31.1

2021-06-10 07:57:25

by Johan Hovold

Subject: Re: [PATCH] USB: serial: cp210x: Fix alternate function for CP2102N QFN20

On Fri, May 28, 2021 at 10:39:31PM +0200, Stefan Agner wrote:
> The QFN20 part has a different GPIO/port function assignment. The
> configuration struct bit field ordered as TX/RX/RS485/WAKEUP/CLK
> which exactly matches GPIO0-3 for QFN24/28. However, QFN20 has a
> different GPIO to primary function assignment.
>
> Special case QFN20 to follow to properly detect which GPIOs are
> available.
>
> Signed-off-by: Stefan Agner <[email protected]>
> ---
> Tested on a custom PCB with a CP2102N QFP20 device. I noticed the bug after
> configuring GPIO.2/3 to be TX/RX LED.

Thanks for fixing this, Stefan.

Nice and clean and patch, and your findings match the datasheet ("Table
4.2. GPIO Pin Alternate Functions").

Now applied for 5.13 with a stable tag.

Johan