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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>,
	Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 12/12] serial: amba-pl011: Support kgdboc_earlycon
Date: Thu,  7 May 2020 13:08:50 -0700	[thread overview]
Message-ID: <20200507130644.v4.12.I8ee0811f0e0816dd8bfe7f2f5540b3dba074fae8@changeid> (raw)
In-Reply-To: <20200507200850.60646-1-dianders@chromium.org>

From: Sumit Garg <sumit.garg@linaro.org>

Implement the read() function in the early console driver. With
recently added kgdboc_earlycon feature, 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: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v4: None
Changes in v3:
- ("serial: amba-pl011: Support kgdboc_earlycon") pulled into my v3.
- Renamed earlycon_kgdboc to kgdboc_earlycon.

Changes in v2: None

 drivers/tty/serial/amba-pl011.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 2296bb0f9578..c010f639298d 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2435,6 +2435,37 @@ static void pl011_early_write(struct console *con, const char *s, unsigned n)
 	uart_console_write(&dev->port, s, n, pl011_putc);
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+static int pl011_getc(struct uart_port *port)
+{
+	if (readl(port->membase + UART01x_FR) & UART01x_FR_RXFE)
+		return NO_POLL_CHAR;
+
+	if (port->iotype == UPIO_MEM32)
+		return readl(port->membase + UART01x_DR);
+	else
+		return readb(port->membase + UART01x_DR);
+}
+
+static int pl011_early_read(struct console *con, char *s, unsigned int n)
+{
+	struct earlycon_device *dev = con->data;
+	int ch, num_read = 0;
+
+	while (num_read < n) {
+		ch = pl011_getc(&dev->port);
+		if (ch == NO_POLL_CHAR)
+			break;
+
+		s[num_read++] = ch;
+	}
+
+	return num_read;
+}
+#else
+#define pl011_early_read NULL
+#endif
+
 /*
  * On non-ACPI systems, earlycon is enabled by specifying
  * "earlycon=pl011,<address>" on the kernel command line.
@@ -2454,6 +2485,7 @@ static int __init pl011_early_console_setup(struct earlycon_device *device,
 		return -ENODEV;
 
 	device->con->write = pl011_early_write;
+	device->con->read = pl011_early_read;
 
 	return 0;
 }
-- 
2.26.2.645.ge9eca65c58-goog


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

Thread overview: 22+ 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 ` [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
2020-05-13 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 ` [PATCH v4 10/12] serial: qcom_geni_serial: Support kgdboc_earlycon Douglas Anderson
2020-05-07 20:08 ` [PATCH v4 11/12] serial: 8250_early: " Douglas Anderson
2020-05-07 20:08 ` Douglas Anderson [this message]
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 16:34   ` Doug Anderson
2020-05-14 16:36     ` Greg Kroah-Hartman
2020-05-19 10:37       ` Daniel Thompson
2020-05-19 10:36 ` Daniel Thompson

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