serial: Combine Tegra and Rockchip UARTs to generic 8250_mmio32

We have two drivers for a 100%-identical peripheral right now, mostly
because we couldn't come up with a good common name for it back when we
checked it in. That seems like a pretty silly reason in the long run.

Both Tegra and Rockchip SoCs contain UARTs that use the common 8250
register interface (at least for the very basic byte-per-byte transmit
and receive parts we care about), memory-mapped with a 32-bit register
stride. This patch combines them to a single 8250_mmio32 driver (which
also fixes a problem when booting Rockchip without serial enabled, since
that driver forgot to check for serial initialization when registering
its console drivers). The register accesses are done using readl/writel
(as Rockchip did before), since the registers are documented as 32-bit
length (with top 24 bits RAZ/WI), although the Tegra SoC doesn't enforce
APB accesses to have the full word length. Also fixed checkpatch stuff.

A day may come when we can also merge this driver into the (completely
different, with more complicated features and #ifdefs) 8250 driver for
x86 (which has MMIO support for 8-bit register stride only), both here
and in coreboot. But it is not this day. This day I just want to get rid
of a 99% identical file without expending too much effort.

BUG=None
TEST=Booted on Veyron_Pinky and Nyan_Blaze with and without serial
enabled, both worked fine (although Veyron has another kernel issue).

Change-Id: I85c004a75cc5aa7cb40098002d3e00a62c1c5f2d
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: e7959c19356d2922aa414866016540ad9ee2ffa8
Original-Change-Id: Ib84d00f52ff2c48398c75f77f6a245e658ffdeb9
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/225102
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9387
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 2 insertions, 7 deletions

diff --git a/payloads/libpayload/Config.in b/payloads/libpayload/Config.in
index cb1d529402..2efd5d673c 100644
--- a/payloads/libpayload/Config.in
+++ b/payloads/libpayload/Config.in
@@ -199,13 +199,8 @@ config S5P_SERIAL_CONSOLE
 	depends on SERIAL_CONSOLE
 	default n
 
-config TEGRA_SERIAL_CONSOLE
-	bool "Tegra SOC compatible serial port driver"
-	depends on SERIAL_CONSOLE
-	default n
-
-config RK_SERIAL_CONSOLE
-	bool "Rockchip SOC serial port driver"
+config 8250_MMIO32_SERIAL_CONSOLE
+	bool "Memory-mapped 8250-compatible serial port driver with 32-bit regs"
 	depends on SERIAL_CONSOLE
 	default n