diff --git a/sys/dev/uart/uart_dev_pl011.c b/sys/dev/uart/uart_dev_pl011.c --- a/sys/dev/uart/uart_dev_pl011.c +++ b/sys/dev/uart/uart_dev_pl011.c @@ -172,6 +172,27 @@ uart_pl011_probe(struct uart_bas *bas) { + /* + * Versions of QEMU before 41f7b58b634e (8.3) reported bogus values for + * this tabel. The PL011 IP is always 32-bits wide and should be shifted + * 2 to match the 4-byte size of the data. QEMU reported these values + * incorrectly before that. + * https://github.com/qemu/qemu/commit/41f7b58b634ec3b60ae874375d2bbb61d790971e + * + * In additon, other hardware vendors also reported this value + * incorrectly. It's not tied to what the ACPI device node is, but was a + * misunderstanding coupled with a Linux driver that didn't need the + * right values. Quirks used to be used to ignore the bad values, now we + * detect the historic mistake and override (to allow for a future where + * we may need to override these values). + * + * PL011 Docs: https://developer.arm.com/documentation/ddi0183/latest/ + */ + if (bas->regshft == 0 || bas->regiowidth == 1) { + bas->regshft = 2; + bas->regiowidth = 4; + } + return (0); } @@ -356,7 +377,8 @@ .uc_ops = &uart_pl011_ops, .uc_range = 0x48, .uc_rclk = 0, - .uc_rshift = 2 + .uc_rshift = 2, + .uc_riowidth = 4, }; UART_CLASS(uart_pl011_class);