[PATCH 2/2] tty: pl011: Work around QDF2400 E44 for earlycon
From: Timur Tabi <hidden>
Date: 2017-02-08 04:07:55
Also in:
linux-serial, lkml
Christopher Covington wrote:
quoted hunk ↗ jump to hunk
The previous change worked around QDF2432v1 and QDF2400v1 SoC erratum 44 for the full-fledged console, when UART AMBA Port (UAP) data is available. Additionally provide a workaround the earlycon case, again checking TXFE == 0 instead of BUSY == 1. As earlycon is operating before UAP data is available, the implementation is different than in the preceding patch. Signed-off-by: Christopher Covington <redacted> --- drivers/tty/serial/amba-pl011.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-)diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 41e51901d6ef..f25e7c994f8e 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c@@ -2411,6 +2411,29 @@ static bool qdf2400_e44(void) { cpu_var_model == MIDR_QCOM_FALKOR_V1); } +#ifdef CONFIG_QCOM_QDF2400_ERRATUM_44 +static void qdf2400_e44_putc(struct uart_port *port, int c) +{ + while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF) + cpu_relax(); + if (port->iotype == UPIO_MEM32) + writel(c, port->membase + UART01x_DR); + else + writeb(c, port->membase + UART01x_DR);
I believe 32-bit writes are safe on QDF2400v1, so I think you technically don't need the UPIO_MEM32 check. Just always call writel.
+ while (!(readl(port->membase + UART01x_FR) & UART011_FR_TXFE))
+ cpu_relax();
+}
+
+static void qdf2400_e44_early_write(struct console *con, const char *s, unsigned n)
+{
+ struct earlycon_device *dev = con->data;
+
+ uart_console_write(&dev->port, s, n, qdf2400_e44_putc);
+}
+#else
+#define qdf2400_e44_early_write pl011_early_write
+#endifSame with patch 1/2. If you change qdf2400_e44(), you don't need the #else block.
quoted hunk ↗ jump to hunk
+ static void pl011_putc(struct uart_port *port, int c) { while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)@@ -2436,7 +2459,10 @@ static int __init pl011_early_console_setup(struct earlycon_device *device, if (!device->port.membase) return -ENODEV; - device->con->write = pl011_early_write; + if (qdf2400_e44()) + device->con->write = qdf2400_e44_early_write; + else + device->con->write = pl011_early_write; return 0; } OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup);
-- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation.