[PATCH] tty: amba-pl011: add support for 32-bit register access for earlycon
From: Timur Tabi <hidden>
Date: 2015-11-07 00:18:23
Also in:
linux-serial
Subsystem:
arm primecell uart pl010 and pl011 drivers, documentation, the rest, tty layer and serial drivers · Maintainers:
Russell King, Jonathan Corbet, Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
Add support the "mmio32" earlycon option for the pl011 device. If specified in the earlycon parameter, all reads/writes to pl011 registers during early console will use 32-bit accessors. Normally the function uses 8-bit writes. Normal console uses the "access_32b" field of the vendor data structure to determine whether the registers needs 32-bit accessors. Early console is used before the vendor data is available, so we need a different mechanism to choose the accessor. Example: earlycon=pl011,mmio32,0x3ced1000 Signed-off-by: Timur Tabi <redacted> --- This patch applies on top of Russell's 12-part amba-pl011.c patchset. Documentation/kernel-parameters.txt | 5 ++++- drivers/tty/serial/amba-pl011.c | 9 ++++++--- 2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 22a4b68..2436f62 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt@@ -992,10 +992,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. unspecified, the h/w is not initialized. pl011,<addr> + pl011,mmio32,<addr> Start an early, polled-mode console on a pl011 serial port at the specified address. The pl011 serial port must already be setup and configured. Options are not - yet supported. + yet supported. If 'mmio32' is specified, then only + the driver will use only 32-bit accessors to read/write + the device registers. msm_serial,<addr> Start an early, polled-mode console on an msm serial
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 373b152..6643ed9 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c@@ -2301,10 +2301,13 @@ static struct console amba_console = { static void pl011_putc(struct uart_port *port, int c) { - while (readl(port->membase + REG_FR) & UART01x_FR_TXFF) + while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF) ; - writeb(c, port->membase + REG_DR); - while (readl(port->membase + REG_FR) & UART01x_FR_BUSY) + if (port->iotype == UPIO_MEM32) + writel(c, port->membase + UART01x_DR); + else + writeb(c, port->membase + UART01x_DR); + while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY) ; }
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