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From: Douglas Anderson <dianders@chromium.org>
To: jason.wessel@windriver.com, daniel.thompson@linaro.org,
	gregkh@linuxfoundation.org
Cc: corbet@lwn.net, frowand.list@gmail.com,
	bjorn.andersson@linaro.org, linux-serial@vger.kernel.org,
	mingo@redhat.com, hpa@zytor.com, jslaby@suse.com,
	kgdb-bugreport@lists.sourceforge.net, sumit.garg@linaro.org,
	will@kernel.org, tglx@linutronix.de, agross@kernel.org,
	catalin.marinas@arm.com, bp@alien8.de,
	Douglas Anderson <dianders@chromium.org>,
	linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 10/12] serial: qcom_geni_serial: Support kgdboc_earlycon
Date: Thu,  7 May 2020 13:08:48 -0700	[thread overview]
Message-ID: <20200507130644.v4.10.If2deff9679a62c1ce1b8f2558a8635dc837adf8c@changeid> (raw)
In-Reply-To: <20200507200850.60646-1-dianders@chromium.org>

Implement the read() function in the early console driver.  With
recent kgdb patches this allows you to use kgdb to debug fairly early
into the system boot.

We only bother implementing this if polling is enabled since kgdb
can't be enabled without that.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

Changes in v4: None
Changes in v3:
- Renamed earlycon_kgdboc to kgdboc_earlycon.
- { ; } ==> { }

Changes in v2: None

 drivers/tty/serial/qcom_geni_serial.c | 32 +++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 6119090ce045..6bace1c6bb09 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1090,6 +1090,36 @@ static void qcom_geni_serial_earlycon_write(struct console *con,
 	__qcom_geni_serial_console_write(&dev->port, s, n);
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+static int qcom_geni_serial_earlycon_read(struct console *con,
+					  char *s, unsigned int n)
+{
+	struct earlycon_device *dev = con->data;
+	struct uart_port *uport = &dev->port;
+	int num_read = 0;
+	int ch;
+
+	while (num_read < n) {
+		ch = qcom_geni_serial_get_char(uport);
+		if (ch == NO_POLL_CHAR)
+			break;
+		s[num_read++] = ch;
+	}
+
+	return num_read;
+}
+
+static void __init qcom_geni_serial_enable_early_read(struct geni_se *se,
+						      struct console *con)
+{
+	geni_se_setup_s_cmd(se, UART_START_READ, 0);
+	con->read = qcom_geni_serial_earlycon_read;
+}
+#else
+static inline void qcom_geni_serial_enable_early_read(struct geni_se *se,
+						      struct console *con) { }
+#endif
+
 static int __init qcom_geni_serial_earlycon_setup(struct earlycon_device *dev,
 								const char *opt)
 {
@@ -1136,6 +1166,8 @@ static int __init qcom_geni_serial_earlycon_setup(struct earlycon_device *dev,
 
 	dev->con->write = qcom_geni_serial_earlycon_write;
 	dev->con->setup = NULL;
+	qcom_geni_serial_enable_early_read(&se, dev->con);
+
 	return 0;
 }
 OF_EARLYCON_DECLARE(qcom_geni, "qcom,geni-debug-uart",
-- 
2.26.2.645.ge9eca65c58-goog


  parent reply	other threads:[~2020-05-07 20:09 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-07 20:08 [PATCH v4 00/12] kgdb: Support late serial drivers; enable early debug w/ boot consoles Douglas Anderson
2020-05-07 20:08 ` Douglas Anderson
2020-05-07 20:08 ` [PATCH v4 01/12] kgdb: Disable WARN_CONSOLE_UNLOCKED for all kgdb Douglas Anderson
2020-05-07 20:08 ` [PATCH v4 02/12] Revert "kgdboc: disable the console lock when in kgdb" Douglas Anderson
2020-05-07 20:08 ` [PATCH v4 03/12] kgdboc: Use a platform device to handle tty drivers showing up late Douglas Anderson
2020-05-18 16:46   ` Daniel Thompson
2020-05-07 20:08 ` [PATCH v4 04/12] kgdb: Delay "kgdbwait" to dbg_late_init() by default Douglas Anderson
2020-05-15 16:18   ` Daniel Thompson
2020-05-07 20:08 ` [PATCH v4 05/12] arm64: Add call_break_hook() to early_brk64() for early kgdb Douglas Anderson
2020-05-07 20:08   ` Douglas Anderson
2020-05-13 23:12   ` Doug Anderson
2020-05-13 23:12     ` Doug Anderson
2020-05-07 20:08 ` [PATCH v4 06/12] kgdb: Prevent infinite recursive entries to the debugger Douglas Anderson
2020-05-07 20:08 ` [PATCH v4 07/12] kgdboc: Remove useless #ifdef CONFIG_KGDB_SERIAL_CONSOLE in kgdboc Douglas Anderson
2020-05-11 16:02   ` Daniel Thompson
2020-05-07 20:08 ` [PATCH v4 08/12] kgdboc: Add kgdboc_earlycon to support early kgdb using boot consoles Douglas Anderson
2020-05-07 20:08 ` [PATCH v4 09/12] Documentation: kgdboc: Document new kgdboc_earlycon parameter Douglas Anderson
2020-05-07 20:08 ` Douglas Anderson [this message]
2020-05-07 20:08 ` [PATCH v4 11/12] serial: 8250_early: Support kgdboc_earlycon Douglas Anderson
2020-05-07 20:08 ` [PATCH v4 12/12] serial: amba-pl011: " Douglas Anderson
2020-05-14 16:21 ` [PATCH v4 00/12] kgdb: Support late serial drivers; enable early debug w/ boot consoles Daniel Thompson
2020-05-14 16:21   ` Daniel Thompson
2020-05-14 16:34   ` Doug Anderson
2020-05-14 16:34     ` Doug Anderson
2020-05-14 16:36     ` Greg Kroah-Hartman
2020-05-14 16:36       ` Greg Kroah-Hartman
2020-05-19 10:37       ` Daniel Thompson
2020-05-19 10:37         ` Daniel Thompson
2020-05-19 10:36 ` Daniel Thompson
2020-05-19 10:36   ` Daniel Thompson

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