[PATCH 6/7] OMAP: Serial: Allow UART parameters to be configured from board file

[Sricharan R]

Hi,
>-----Original Message-----
>From: Govindraj [mailto:govindraj.ti at gmail.com]
>Sent: Wednesday, March 02, 2011 1:11 PM
>To: Sricharan R
>Cc: Govindraj.R; linux-omap at vger.kernel.org;
linux-serial at vger.kernel.org;
>linux-arm-kernel at lists.infradead.org; Jon Hunter; Tony Lindgren; Benoit
>Cousson; Kevin Hilman; Paul Walmsley; Rajendra Nayak; Deepak Kattungal
>Subject: Re: [PATCH 6/7] OMAP: Serial: Allow UART parameters to be
>configured from board file
>
>On Wed, Mar 2, 2011 at 12:46 AM, Sricharan R <r.sricharan at ti.com> wrote:
>> Hi,
>>>diff --git a/arch/arm/mach-omap2/serial.c
b/arch/arm/mach-omap2/serial.c
>>>index 755f4aa..530e9e3 100644
>>>--- a/arch/arm/mach-omap2/serial.c
>>>+++ b/arch/arm/mach-omap2/serial.c
>>>@@ -44,6 +44,15 @@
>>>
>>> static int omap_uart_con_id __initdata = -1;
>>>
>>>+static struct omap_uart_port_info omap_serial_default_info[] = {
>>>+      {
>>>+              .dma_enabled    = 0,
>>>+              .dma_rx_buf_size = DEFAULT_RXDMA_BUFSIZE,
>>>+              .dma_rx_timeout = DEFAULT_RXDMA_TIMEOUT,
>>>+              .idle_timeout   = DEFAULT_IDLE_TIMEOUT,
>>>+      },
>>>+};
>>>+
>>> static int uart_idle_hwmod(struct omap_device *od)
>>> {
>>>       omap_hwmod_idle(od->hwmods[0]);
>>>@@ -66,6 +75,54 @@ static struct omap_device_pm_latency
>> omap_uart_latency[]
>>>= {
>>>       },
>>> };
>>>
>>>+#ifdef CONFIG_OMAP_MUX
>>>+static struct omap_device_pad default_serial0_pads[] __initdata = {
>>>+      {
>>>+              .name   = "uart1_rx.uart1_rx",
>>>+              .flags  = OMAP_DEVICE_PAD_REMUX |
OMAP_DEVICE_PAD_WAKEUP,
>>>+              .enable = OMAP_MUX_MODE0,
>>>+      },
>>>+};
>>>+
>>>+static struct omap_device_pad default_serial1_pads[] __initdata = {
>>>+      {
>>>+              .name   = "uart2_rx.uart2_rx",
>>>+              .flags  = OMAP_DEVICE_PAD_REMUX |
OMAP_DEVICE_PAD_WAKEUP,
>>>+              .enable = OMAP_MUX_MODE0,
>>>+      },
>>>+};
>>>+
>>>+static struct omap_device_pad default_serial2_pads[] __initdata = {
>>>+      {
>>>+              .name   = "uart3_rx_irrx.uart3_rx_irrx",
>>>+              .flags  = OMAP_DEVICE_PAD_REMUX |
OMAP_DEVICE_PAD_WAKEUP,
>>>+              .enable = OMAP_MUX_MODE0,
>>>+      },
>>>+};
>>>+
>>>+static struct omap_device_pad default_omap36xx_serial3_pads[]
__initdata
>> =
>>>{
>>>+      {
>>>+              .name   = "gpmc_wait3.uart4_rx",
>>>+              .flags  = OMAP_DEVICE_PAD_REMUX |
OMAP_DEVICE_PAD_WAKEUP,
>>>+              .enable = OMAP_MUX_MODE2,
>>>+      },
>>>+};
>>>+
>>>+static struct omap_device_pad default_omap4_serial3_pads[] __initdata
=
>> {
>>>+      {
>>>+              .name   = "uart4_rx.uart4_rx",
>>>+              .flags  = OMAP_DEVICE_PAD_REMUX |
OMAP_DEVICE_PAD_WAKEUP,
>>>+              .enable = OMAP_MUX_MODE0,
>>>+      },
>>>+};
>> Here only the UART RX pins are muxed, so what about the cts, rts, tx
>pins?
>
>The intention here is to enable wakeup capabilities for uart rx pad.
>
>AFAIK most of the boards are currently dependent on bootloader for
>uart-muxing if any board is not dependent on bootloader then we
>can use omap_serial_init_port along with board_mux_info from board.
>
Yes. The idea is to be independent of the bootloaders for mux settings.

>Prior to this change uart wakeup is based on rx_pad and we were
populating
>offset and using omap_ctrl api's to read/write which is cleaned up now.
>Most of boards are dependent on uart-rx wakeup to avoid breaking any
>board support we
>are using omap_serial_init by filling default values, which provides
>us with same
>environment but with right approach towards handling mux data with a
>handshake with
>hwmod framework.
>
Now, in this change only the RX pin is configured. So if some board uses
omap_serial_init then only the RX is going to be configured.
How will they configure the rest of the pins?
They cannot call omap_serial_init_port after this just to configure the
rest of the mux pins( cts, rts, tx).

So data which is passed from omap_serial_init should have the
configuration
for all the pins, and this default data should be consistent across
atleast
some boards, so that they can use this. This will reduce the data
duplication across board files.

If this is not true, then all the pads can be configured from the board
files itself using omap_serial_init_port and you can set the required
RX wakeup capability there as well.

>So if any board needs specific mux they can go ahead and add required
>mux data in
>board file and use map_serial_init_port instead of current
>omap_serial_init.
>
>
>> Is it consistent that across all socs that only UART3 would have
>UART/IRDA
>> functions capability so that serial2 pads can always be called
"rx_irxx"
>> ?.
>
>Yes from OMAP2420 to OMAP4430 uart3 can used as irda.
>
Ok.
>--
>Thanks,
>Govindraj.R