[Xen-changelog] [xen master] xen/serial: setup UART idle mode for OMAP

[patchbot@xxxxxxx]

commit dcd84861b0b01b8895716d4c803c9d24c31c8cab
Author:     Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>
AuthorDate: Mon Dec 8 15:51:47 2014 +0200
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Tue Dec 16 12:41:06 2014 +0000

    xen/serial: setup UART idle mode for OMAP
    
    The UART is not able to receive bytes when idle mode is not configured
    properly, therefore setup the UART with autoidle and wakeup enabled.
    
    Older Linux kernels (for example 3.8) configure hwmods for all devices
    even if the device tree nodes for those devices is absent in device
    tree, thus UART idle mode is configured too.  With such kernels we can
    workaround the issue by adding a fake node in the UART containing this
    MMIO range, which is therefore mapped by Xen to dom0, which
    reconfigures the UART, causing things to work normally.
    
    Newer Linux Kernels (3.12 and beyond) do not configure idle mode for
    UART and so this hack no longer works.
    
    Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    [ ijc -- updated commit message as discussed ]
---
 xen/drivers/char/omap-uart.c |    3 +++
 xen/include/xen/8250-uart.h  |    4 ++++
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/xen/drivers/char/omap-uart.c b/xen/drivers/char/omap-uart.c
index a798b8d..16d1454 100644
--- a/xen/drivers/char/omap-uart.c
+++ b/xen/drivers/char/omap-uart.c
@@ -195,6 +195,9 @@ static void __init omap_uart_init_preirq(struct serial_port 
*port)
     omap_write(uart, UART_MCR, UART_MCR_DTR|UART_MCR_RTS);
 
     omap_write(uart, UART_OMAP_MDR1, UART_OMAP_MDR1_16X_MODE);
+
+    /* setup iddle mode */
+    omap_write(uart, UART_SYSC, OMAP_UART_SYSC_DEF_CONF);
 }
 
 static void __init omap_uart_init_postirq(struct serial_port *port)
diff --git a/xen/include/xen/8250-uart.h b/xen/include/xen/8250-uart.h
index a682bae..304b9dd 100644
--- a/xen/include/xen/8250-uart.h
+++ b/xen/include/xen/8250-uart.h
@@ -32,6 +32,7 @@
 #define UART_MCR          0x04    /* Modem control        */
 #define UART_LSR          0x05    /* line status          */
 #define UART_MSR          0x06    /* Modem status         */
+#define UART_SYSC         0x15    /* System configuration register */
 #define UART_USR          0x1f    /* Status register (DW) */
 #define UART_DLL          0x00    /* divisor latch (ls) (DLAB=1) */
 #define UART_DLM          0x01    /* divisor latch (ms) (DLAB=1) */
@@ -145,6 +146,9 @@
 /* SCR register bitmasks */
 #define OMAP_UART_SCR_RX_TRIG_GRANU1_MASK (1 << 7)
 
+/* System configuration register */
+#define OMAP_UART_SYSC_DEF_CONF 0x0d /* autoidle mode, wakeup is enabled */
+
 #endif /* __XEN_8250_UART_H__ */
 
 /*
--
generated by git-patchbot for /home/xen/git/xen.git#master

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog