Re: [PATCH 2/3] omap-serial: Add minimal device tree support

Rob Herring
2011-11-16T14:59:43Z

On 11/16/2011 05:02 AM, Rajendra Nayak wrote:
> Adapt the driver to device tree and pass minimal platform
> data from device tree needed for console boot.
> No power management features will be suppported for now
> since it requires more tweaks around OCP settings
> to toggle forceidle/noidle/smaridle bits and handling
> remote wakeup and dynamic muxing.
>
> Signed-off-by: Rajendra Nayak <rnayak@ti.com>
> ---
> .../devicetree/bindings/serial/omap_serial.txt | 9 +++++
> drivers/tty/serial/omap-serial.c | 37 +++++++++++++++++++-
> 2 files changed, 45 insertions(+), 1 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/serial/omap_serial.txt
>
> diff --git a/Documentation/devicetree/bindings/serial/omap_serial.txt b/Documentation/devicetree/bindings/serial/omap_serial.txt
> new file mode 100644
> index 0000000..bf6d631
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/serial/omap_serial.txt
> @@ -0,0 +1,9 @@
> +OMAP UART controller
> +
> +Required properties:
> +- compatible : should be "ti,omap-uart"

This seems too generic. There are no h/w differences in the uart since
the 1st OMAP1 device?

> +- ti,hwmods : Must be "uart<n>", n being the instance number (1-based)
> +
> +Optional properties:
> +- clock-frequency : frequency of the clock input to the UART
> +- ti,console_hwmod : boolean, UART used as debug console
> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
> index e1c8527..e3419c6 100644
> --- a/drivers/tty/serial/omap-serial.c
> +++ b/drivers/tty/serial/omap-serial.c
> @@ -38,6 +38,7 @@
> #include <linux/serial_core.h>
> #include <linux/irq.h>
> #include <linux/pm_runtime.h>
> +#include <linux/of.h>
>
> #include <plat/dma.h>
> #include <plat/dmtimer.h>
> @@ -1322,6 +1323,22 @@ static void uart_tx_dma_callback(int lch, u16 ch_status, void *data)
> return;
> }
>
> +static struct omap_uart_port_info *of_get_uart_port_info(struct device *dev)
> +{
> + struct omap_uart_port_info *omap_up_info;
> +
> + omap_up_info = devm_kzalloc(dev, sizeof(*omap_up_info), GFP_KERNEL);
> + if (!omap_up_info)
> + return NULL; /* out of memory */
> +
> + of_property_read_u32(dev->of_node, "clock-frequency",
> + &(*omap_up_info).uartclk);

&omap_up_info->uartclk

You want 0 to be the default freq?

> +
> + return omap_up_info;
> +}
> +
> +static atomic_t omap_uart_next_id = ATOMIC_INIT(0);
> +
> static int serial_omap_probe(struct platform_device *pdev)
> {
> struct uart_omap_port *up;
> @@ -1329,6 +1346,11 @@ static int serial_omap_probe(struct platform_device *pdev)
> struct omap_uart_port_info *omap_up_info = pdev->dev.platform_data;
> int ret = -ENOSPC;
>
> + if (pdev->dev.of_node) {
> + omap_up_info = of_get_uart_port_info(&pdev->dev);
> + pdev->id = atomic_inc_return(&omap_uart_next_id) - 1;

I don't think a driver changing this value is a good idea. Look at other
serial drivers like iMX for how they use aliases.

> + }
> +
> mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> if (!mem) {
> dev_err(&pdev->dev, "no mem resource?\n");
> @@ -1523,7 +1545,7 @@ static int serial_omap_runtime_suspend(struct device *dev)
> if (!up)
> return -EINVAL;
>
> - if (!pdata->enable_wakeup)
> + if (!pdata || !pdata->enable_wakeup)
> return 0;
>
> if (pdata->get_context_loss_count)
> @@ -1582,12 +1604,25 @@ static const struct dev_pm_ops serial_omap_dev_pm_ops = {
> serial_omap_runtime_resume, NULL)
> };
>
> +#if defined(CONFIG_OF)
> +static const struct of_device_id omap_serial_of_match[] = {
> + {
> + .compatible = "ti,omap-uart",
> + },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, omap_serial_of_match);
> +#else
> +#define omap_serial_of_match NULL
> +#endif
> +
> static struct platform_driver serial_omap_driver = {
> .probe = serial_omap_probe,
> .remove = serial_omap_remove,
> .driver = {
> .name = DRIVER_NAME,
> .pm = &serial_omap_dev_pm_ops,
> + .of_match_table = omap_serial_of_match,

Use of_match_ptr and get rid of the #else

Rob