[PATCH 2/3] serial: 8250_early: Add support for regshift
From: Jon Hunter <hidden>
Date: 2016-01-12 10:33:28
Also in:
linux-serial, linux-tegra
Subsystem:
8250/16?50 (and clone uarts) serial driver, the rest, tty layer and serial drivers · Maintainers:
Greg Kroah-Hartman, Linus Torvalds, Jiri Slaby
Possibly related (same subject, not in this thread)
- 2016-01-12 · Re: [PATCH 2/3] serial: 8250_early: Add support for regshift · Peter Hurley <hidden>
- 2016-01-12 · Re: [PATCH 2/3] serial: 8250_early: Add support for regshift · Jon Hunter <hidden>
- 2016-01-12 · Re: [PATCH 2/3] serial: 8250_early: Add support for regshift · Peter Hurley <hidden>
The 8250 early console assumes a default regshift for each iotype. This does not work for all devices. For example, Tegra UARTs use a iotype of UPIO_MEM with a regshift of 2 because the registers are 32-bit aligned and permit byte access. If the regshift is specified (for example, via device-tree), then use the value provided and otherwise revert to the defaults assumed for each iotype. Signed-off-by: Jon Hunter <redacted> --- Please note that today for Tegra, early console is supported by passing the boot parameter "earlycon=uart8250,mmio32,0xXXXXXXXX". While this works and we could use UPIO_MEM32 for tegra, this would mean changing all the DT source files for Tegra to add the "reg-io-width" property. IMO it seems better to make early console for 8250 work in the same way as the normal 8250 console and support regshift. drivers/tty/serial/8250/8250_early.c | 36 ++++++++++++++++++++++++++---------- 1 file changed, 26 insertions(+), 10 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index af62131af21e..758054957788 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c@@ -41,15 +41,15 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse { switch (port->iotype) { case UPIO_MEM: - return readb(port->membase + offset); + return readb(port->membase + (offset << port->regshift)); case UPIO_MEM16: - return readw(port->membase + (offset << 1)); + return readw(port->membase + (offset << port->regshift)); case UPIO_MEM32: - return readl(port->membase + (offset << 2)); + return readl(port->membase + (offset << port->regshift)); case UPIO_MEM32BE: - return ioread32be(port->membase + (offset << 2)); + return ioread32be(port->membase + (offset << port->regshift)); case UPIO_PORT: - return inb(port->iobase + offset); + return inb(port->iobase + (offset << port->regshift)); default: return 0; }
@@ -59,19 +59,19 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int { switch (port->iotype) { case UPIO_MEM: - writeb(value, port->membase + offset); + writeb(value, port->membase + (offset << port->regshift)); break; case UPIO_MEM16: - writew(value, port->membase + (offset << 1)); + writew(value, port->membase + (offset << port->regshift)); break; case UPIO_MEM32: - writel(value, port->membase + (offset << 2)); + writel(value, port->membase + (offset << port->regshift)); break; case UPIO_MEM32BE: - iowrite32be(value, port->membase + (offset << 2)); + iowrite32be(value, port->membase + (offset << port->regshift)); break; case UPIO_PORT: - outb(value, port->iobase + offset); + outb(value, port->iobase + (offset << port->regshift)); break; } }
@@ -128,6 +128,22 @@ int __init early_serial8250_setup(struct earlycon_device *device, if (!(device->port.membase || device->port.iobase)) return -ENODEV; + /* + * If regshift is not specified, then assume the + * following defaults for the below iotypes. + */ + if (!device->port.regshift) { + switch (device->port.iotype) { + case UPIO_MEM16: + device->port.regshift = 1; + break; + case UPIO_MEM32: + case UPIO_MEM32BE: + device->port.regshift = 2; + break; + } + } + if (!device->baud) { struct uart_port *port = &device->port; unsigned int ier;
--
2.1.4