linux-kernel - [PATCH 05/13] tty: serial: samsung: add gs101 earlycon support

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Message-ID: <20231214105243.3707730-6-tudor.ambarus@linaro.org>
Date:   Thu, 14 Dec 2023 10:52:35 +0000
From:   Tudor Ambarus <tudor.ambarus@...aro.org>
To:     peter.griffin@...aro.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, mturquette@...libre.com,
        sboyd@...nel.org, conor+dt@...nel.org, andi.shyti@...nel.org,
        alim.akhtar@...sung.com, gregkh@...uxfoundation.org,
        jirislaby@...nel.org, catalin.marinas@....com, will@...nel.org,
        s.nawrocki@...sung.com, tomasz.figa@...il.com,
        cw00.choi@...sung.com, arnd@...db.de, semen.protsenko@...aro.org
Cc:     andre.draszik@...aro.org, saravanak@...gle.com,
        willmcvicker@...gle.com, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-serial@...r.kernel.org,
        Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH 05/13] tty: serial: samsung: add gs101 earlycon support

GS101 only allows 32-bit register accesses. If using 8-bit register
accesses on gs101, a SError Interrupt is raised causing the system
unusable.

Force the reg accesses to MMIO32 regardless of the user's settings.
This is a common practice for such earlycons (bcm2835aux, uniphier,
lpuart32), in order to avoid crashing the kernel with a wrong early
console definition.

Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
---
 drivers/tty/serial/samsung_tty.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index 66bd6c090ace..19cd3e6a9b6e 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -2787,6 +2787,17 @@ OF_EARLYCON_DECLARE(exynos4210, "samsung,exynos4210-uart",
 OF_EARLYCON_DECLARE(artpec8, "axis,artpec8-uart",
 			s5pv210_early_console_setup);
 
+static int __init gs101_early_console_setup(struct earlycon_device *device,
+					    const char *opt)
+{
+	/* gs101 always expects MMIO32 register accesses. */
+	device->port.iotype = UPIO_MEM32;
+
+	return s5pv210_early_console_setup(device, opt);
+}
+
+OF_EARLYCON_DECLARE(gs101, "google,gs101-uart", gs101_early_console_setup);
+
 /* Apple S5L */
 static int __init apple_s5l_early_console_setup(struct earlycon_device *device,
 						const char *opt)
-- 
2.43.0.472.g3155946c3a-goog