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Date: Sat, 18 Jun 2011 10:19:34 -0600
From: Grant Likely <grant.likely@secretlab.ca>
To: Shawn Guo <shawn.guo@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org, patches@linaro.org,
        netdev@vger.kernel.org, devicetree-discuss@lists.ozlabs.org,
        Jason Liu <jason.hui@linaro.org>, linux-kernel@vger.kernel.org,
        Jeremy Kerr <jeremy.kerr@canonical.com>,
        Sascha Hauer <s.hauer@pengutronix.de>
Subject: Re: [PATCH 1/3] serial/imx: add device tree support
Message-ID: <20110618161934.GH8195@ponder.secretlab.ca>
References: <1308410354-21387-1-git-send-email-shawn.guo@linaro.org>
 <1308410354-21387-2-git-send-email-shawn.guo@linaro.org>
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On Sat, Jun 18, 2011 at 11:19:12PM +0800, Shawn Guo wrote:
> It adds device tree data parsing support for imx tty/serial driver.
> 
> Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
> Signed-off-by: Jason Liu <jason.hui@linaro.org>
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  .../bindings/tty/serial/fsl-imx-uart.txt           |   21 +++++
>  drivers/tty/serial/imx.c                           |   81 +++++++++++++++++---
>  2 files changed, 92 insertions(+), 10 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/tty/serial/fsl-imx-uart.txt
> 
> diff --git a/Documentation/devicetree/bindings/tty/serial/fsl-imx-uart.txt b/Documentation/devicetree/bindings/tty/serial/fsl-imx-uart.txt
> new file mode 100644
> index 0000000..7648e17
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/tty/serial/fsl-imx-uart.txt
> @@ -0,0 +1,21 @@
> +* Freescale i.MX Universal Asynchronous Receiver/Transmitter (UART)
> +
> +Required properties:
> +- compatible : should be "fsl,<soc>-uart", "fsl,imx-uart"

I'd make this "fsl,<soc>-uart", "fsl,imx51-uart"

It's better to anchor these things on real silicon, or a real ip block
specification rather than something pseudo-generic.  Subsequent chips,
like the imx53, should simply claim compatibility with the older
fsl,imx51-uart.

(in essence, "fsl,imx51-uart" becomes the generic string without the
downside of having no obvious recourse when new silicon shows up that
is an imx part, but isn't compatible with the imx51 uart.

> +- reg : address and length of the register set for the device
> +- interrupts : should contain uart interrupt
> +- id : should be the port ID defined by soc
> +
> +Optional properties:
> +- fsl,has-rts-cts : indicate it has rts-cts
> +- fsl,irda-mode : support irda mode
> +
> +Example:
> +
> +uart@73fbc000 {
> +	compatible = "fsl,imx51-uart", "fsl,imx-uart";
> +	reg = <0x73fbc000 0x4000>;
> +	interrupts = <31>;
> +	id = <1>;
> +	fsl,has-rts-cts;
> +};
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index a544731..2769353 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -45,6 +45,8 @@
>  #include <linux/delay.h>
>  #include <linux/rational.h>
>  #include <linux/slab.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
>  
>  #include <asm/io.h>
>  #include <asm/irq.h>
> @@ -1223,6 +1225,63 @@ static int serial_imx_resume(struct platform_device *dev)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_OF
> +static int serial_imx_probe_dt(struct imx_port *sport,
> +		struct platform_device *pdev)
> +{
> +	struct device_node *node = pdev->dev.of_node;
> +	const __be32 *line;
> +
> +	if (!node)
> +		return -ENODEV;
> +
> +	line = of_get_property(node, "id", NULL);
> +	if (!line)
> +		return -ENODEV;
> +
> +	sport->port.line = be32_to_cpup(line) - 1;

Hmmm, I really would like to be rid of this.  Instead, if uarts must
be enumerated, the driver should look for a /aliases/uart* property
that matches the of_node.  Doing it that way is already established in
the OpenFirmware documentation, and it ensures there are no overlaps
in the global namespace.

We do need some infrastructure to make that easier though.  Would you
have time to help put that together?

> +
> +	if (of_get_property(node, "fsl,has-rts-cts", NULL))
> +		sport->have_rtscts = 1;
> +
> +	if (of_get_property(node, "fsl,irda-mode", NULL))
> +		sport->use_irda = 1;
> +
> +	return 0;
> +}
> +
> +static struct of_device_id imx_uart_dt_ids[] = {
> +	{ .compatible = "fsl,imx-uart" },
> +	{},
> +};
> +#else
> +static int serial_imx_probe_dt(struct imx_port *sport,
> +		struct platform_device *pdev)
> +{
> +	return -ENODEV;
> +}
> +#define imx_uart_dt_ids NULL
> +#endif
> +
> +static int serial_imx_probe_pdata(struct imx_port *sport,
> +		struct platform_device *pdev)
> +{
> +	struct imxuart_platform_data *pdata = pdev->dev.platform_data;
> +
> +	if (!pdata)
> +		return 0;
> +
> +	if (pdata->flags & IMXUART_HAVE_RTSCTS)
> +		sport->have_rtscts = 1;
> +
> +	if (pdata->flags & IMXUART_IRDA)
> +		sport->use_irda = 1;
> +
> +	sport->port.line = pdev->id;
> +
> +	return 0;
> +}
> +
>  static int serial_imx_probe(struct platform_device *pdev)
>  {
>  	struct imx_port *sport;
> @@ -1235,6 +1294,12 @@ static int serial_imx_probe(struct platform_device *pdev)
>  	if (!sport)
>  		return -ENOMEM;
>  
> +	ret = serial_imx_probe_dt(sport, pdev);
> +	if (ret == -ENODEV)
> +		ret = serial_imx_probe_pdata(sport, pdev);
> +	if (ret)
> +		goto free;
> +
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	if (!res) {
>  		ret = -ENODEV;
> @@ -1259,7 +1324,6 @@ static int serial_imx_probe(struct platform_device *pdev)
>  	sport->port.fifosize = 32;
>  	sport->port.ops = &imx_pops;
>  	sport->port.flags = UPF_BOOT_AUTOCONF;
> -	sport->port.line = pdev->id;
>  	init_timer(&sport->timer);
>  	sport->timer.function = imx_timeout;
>  	sport->timer.data     = (unsigned long)sport;
> @@ -1273,17 +1337,13 @@ static int serial_imx_probe(struct platform_device *pdev)
>  
>  	sport->port.uartclk = clk_get_rate(sport->clk);
>  
> -	imx_ports[pdev->id] = sport;
> +	if (imx_ports[sport->port.line]) {
> +		ret = -EBUSY;
> +		goto clkput;
> +	}
> +	imx_ports[sport->port.line] = sport;
>  
>  	pdata = pdev->dev.platform_data;
> -	if (pdata && (pdata->flags & IMXUART_HAVE_RTSCTS))
> -		sport->have_rtscts = 1;
> -
> -#ifdef CONFIG_IRDA
> -	if (pdata && (pdata->flags & IMXUART_IRDA))
> -		sport->use_irda = 1;
> -#endif
> -
>  	if (pdata && pdata->init) {
>  		ret = pdata->init(pdev);
>  		if (ret)
> @@ -1344,6 +1404,7 @@ static struct platform_driver serial_imx_driver = {
>  	.driver		= {
>  		.name	= "imx-uart",
>  		.owner	= THIS_MODULE,
> +		.of_match_table = imx_uart_dt_ids,
>  	},
>  };
>  
> -- 
> 1.7.4.1
> 
> _______________________________________________
> devicetree-discuss mailing list
> devicetree-discuss@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/devicetree-discuss
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