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SubjectRe: [PATCH 2/6] tty: serial: lpuart: add little endian 32 bit register support
On Wed, May 10, 2017 at 11:58 AM, Stefan Agner <stefan@agner.ch> wrote:
> On 2017-05-09 00:50, Dong Aisheng wrote:
>> It's based on the exist lpuart32 read/write implementation.
>>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> Cc: Jiri Slaby <jslaby@suse.com> (supporter:TTY LAYER)
>> Cc: Fugang Duan <fugang.duan@nxp.com>
>> Cc: Stefan Agner <stefan@agner.ch>
>> Cc: Mingkai Hu <Mingkai.Hu@nxp.com>
>> Cc: Yangbo Lu <yangbo.lu@nxp.com>
>> Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
>> ---
>> drivers/tty/serial/fsl_lpuart.c | 12 ++++++++++--
>> 1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
>> index cd4e905..bddd041 100644
>> --- a/drivers/tty/serial/fsl_lpuart.c
>> +++ b/drivers/tty/serial/fsl_lpuart.c
>> @@ -231,6 +231,8 @@
>> #define DEV_NAME "ttyLP"
>> #define UART_NR 6
>>
>> +static bool lpuart_is_be;
>> +
>
> Other LS1021a IP's such as SPI use the big-endian device tree property
> along with regmap.
>
> See e.g.
> drivers/spi/spi-fsl-dspi.c
>
> (Used in vf610 in little endian mode and ls1021a in big endian)
>
> Not sure if we want to switch to regmap, but you can also get the
> property using of_get_property.
>
> The ls1021a lpuart node do not specify big-endian at the moment (would
> probably good to add it),

That's why i did not check for little-endian initially.

> so I would leave big-endian the driver default
> and check for little-endian for the new device and check whether that is
> specified:
> of_get_property(dn, "little-endian", NULL)

As we already have the platform data, it's not too necessary to get the endian
from device tree.

Regards
Dong Aisheng

>
> --
> Stefan
>
>> struct lpuart_port {
>> struct uart_port port;
>> struct clk *clk;
>> @@ -260,6 +262,7 @@ struct lpuart_port {
>>
>> struct lpuart_soc_data {
>> bool is_32;
>> + bool is_be;
>> };
>>
>> static struct lpuart_soc_data vf_data = {
>> @@ -268,6 +271,7 @@ static struct lpuart_soc_data vf_data = {
>>
>> static struct lpuart_soc_data ls_data = {
>> .is_32 = true,
>> + .is_be = true,
>> };
>>
>> static const struct of_device_id lpuart_dt_ids[] = {
>> @@ -282,12 +286,15 @@ static void lpuart_dma_tx_complete(void *arg);
>>
>> static u32 lpuart32_read(void __iomem *addr)
>> {
>> - return ioread32be(addr);
>> + return lpuart_is_be ? ioread32be(addr) : readl(addr);
>> }
>>
>> static void lpuart32_write(u32 val, void __iomem *addr)
>> {
>> - iowrite32be(val, addr);
>> + if (lpuart_is_be)
>> + iowrite32be(val, addr);
>> + else
>> + writel(val, addr);
>> }
>>
>> static void lpuart_stop_tx(struct uart_port *port)
>> @@ -2000,6 +2007,7 @@ static int lpuart_probe(struct platform_device *pdev)
>> }
>> sport->port.line = ret;
>> sport->lpuart32 = sdata->is_32;
>> + lpuart_is_be = sdata->is_be;
>>
>> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> sport->port.membase = devm_ioremap_resource(&pdev->dev, res);

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