Subject: [PATCH 1/3] ARM: pxa: Add DT support to pxa2xx-uart

From: [email-masked] (Marek Vasut)
Date: Wed, 2 Nov 2011 15:30:24 +0100

> On 11/01/2011 03:15 PM, Marek Vasut wrote:
> >> On 11/01/2011 01:32 PM, Marek Vasut wrote:
> >>> Add device tree binding for PXA2xx UARTs. Tested on Vpac270 board.
> >>> 
> >>> Signed-off-by: Marek Vasut <[email-masked]>
> >>> Cc: Arnd Bergmann <[email-masked]>
> >>> Cc: Grant Likely <[email-masked]>
> >>> ---
> >>> 
> >>>  drivers/tty/serial/pxa.c |   50
> >>>  +++++++++++++++++++++++++++++++++++++++++++-- 1 files changed, 47
> >>>  insertions(+), 3 deletions(-)
> >>> 
> >>> diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c
> >>> index 531931c..836cbb4 100644
> >>> --- a/drivers/tty/serial/pxa.c
> >>> +++ b/drivers/tty/serial/pxa.c
> >>> @@ -43,6 +43,8 @@
> >>> 
> >>>  #include <linux/clk.h>
> >>>  #include <linux/io.h>
> >>>  #include <linux/slab.h>
> >>> 
> >>> +#include <linux/of.h>
> >>> +#include <linux/of_device.h>
> >>> 
> >>>  struct uart_pxa_port {
> >>>  
> >>>  	struct uart_port        port;
> >>> 
> >>> @@ -761,11 +763,50 @@ static const struct dev_pm_ops serial_pxa_pm_ops
> >>> = {
> >>> 
> >>>  };
> >>>  #endif
> >>> 
> >>> +#ifdef CONFIG_OF
> >>> +static struct of_device_id serial_pxa_dt_ids[] = {
> >>> +	{ .compatible = "marvell,pxa2xx-uart" },
> >>> +	{ /* sentinel */ }
> >>> +};
> >>> +MODULE_DEVICE_TABLE(of, serial_pxa_dt_ids);
> >>> +
> >>> +static int serial_pxa_probe_dt(struct platform_device *pdev, int
> >>> *portid) +{
> >>> +	struct device_node *np = pdev->dev.of_node;
> >>> +	static int portnum;
> >>> +
> >>> +	if (!np)
> >>> +		return -ENODEV;
> >>> +
> >>> +	/* PXA has up to four UART ports */
> >>> +	*portid = portnum++;
> >> 
> >> You have no guarantee of the probe ordering yet are dependent on the
> >> number later on to set the name.
> > 
> > The probe order should be the one according to the order of ports in DT,
> > right ?
> 
> Maybe so, but there is no guarantee of that. If you can avoid it that
> would be best, but I think most serial drivers end up with some sort of
> index. Look at the recent DT support for i.MX uart and the alias support.
> 
> >>> +	if (*portid >= 4)
> >>> +		return -ENODEV;
> >>> +
> >>> +	/* Check if we're probing compatible ports only! */
> >>> +	if (of_get_property(np, "marvell,pxa250", NULL))
> >>> +		if (!cpu_is_pxa25x())
> >>> +			return -EINVAL;
> >> 
> >> if dev->of_node is set, then you already know you matched against
> >> marvell,pxa2xx-uart,
> > 
> > Yes, I'm checking if the port has an additional parameter
> > "marvell,pxa250" set, which means it should check if the CPU is pxa250.
> 
> If you have differences between pxa250 uart and other pxa2xx uart
> versions, then the compatible string should reflect this (i.e.
> marvell,pxa250-uart). Generally, you want to be specific with compatible
> strings. To do it generically, use the oldest chip name and newer chips
> can be compatible. For example, a pxa250 uart can use
> marvell,pxa250-uart and every other chip can use marvell,pxa210-uart.
> 
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +#else
> >>> +static inline int serial_pxa_probe_dt(struct platform_device *pdev,
> >>> int *portid) +{
> >>> +	return 0;
> >>> +}
> >>> +#endif
> >>> +
> >>> 
> >>>  static int serial_pxa_probe(struct platform_device *dev)
> >>>  {
> >>>  
> >>>  	struct uart_pxa_port *sport;
> >>>  	struct resource *mmres, *irqres;
> >>>  	int ret;
> >>> 
> >>> +	int portid = dev->id;
> >>> +
> >>> +	ret = serial_pxa_probe_dt(dev, &portid);
> >>> +	if (ret == -EINVAL)
> >>> +		return 0;
> >> 
> >> What about non-DT probing when CONFIG_OF is enabled?
> > 
> > Then ret isn't -EINVAL and it should be ok ?
> 
> Ahh, yes you're right.
> 
> Rob

Thanks Rob,

I'm quite new to this DT stuff. This was very helpful though, expect new load of 
patches soon. Thanks!