RE: [EXT] [PATCH v3] serial: 8250_fsl: Add ACPI support

["Vabhav Sharma (OSS)" <vabhav.sharma@oss.nxp.com>]

> -----Original Message-----
> From: kuldip dwivedi <kuldip.dwivedi@puresoftware.com>
> Sent: Saturday, August 29, 2020 8:13 PM
> To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; Jiri Slaby
> <jirislaby@kernel.org>; Dmitry Safonov <0x7f454c46@gmail.com>; linux-
> serial@vger.kernel.org
> Cc: Vabhav Sharma <vabhav.sharma@nxp.com>; Pankaj Bansal
> <pankaj.bansal@nxp.com>; Varun Sethi <V.Sethi@nxp.com>; Arokia Samy
> <arokia.samy@nxp.com>; kuldip dwivedi
> <kuldip.dwivedi@puresoftware.com>
> Subject: [EXT] [PATCH v3] serial: 8250_fsl: Add ACPI support
> 
> Caution: EXT Email
> 
> This adds support for ACPI enumerated FSL 16550 UARTs.
> For supporting ACPI, I added a wrapper so that this driver can be used if
> firmware has exposed the HID "NXP0018" in DSDT table.
> 
> This will be built as object file if config "SERIAL_8250_FSL"
> is enabled which depends on config "SERIAL_8250_CONSOLE".
> 
> Signed-off-by: kuldip dwivedi <kuldip.dwivedi@puresoftware.com>
> ---
> 
> Notes:
>     1. Move Copyright and File description at top of the file
>     2. Add ACPI wrapper code within CONFIG_ACPI macro
>     3. this change is tested with DT and ACPI boot on LS1046A platform
> 
>  drivers/tty/serial/8250/8250_fsl.c | 108 +++++++++++++++++++++++++++--
>  1 file changed, 101 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_fsl.c
> b/drivers/tty/serial/8250/8250_fsl.c
> index 0d0c80905c58..68bfbf392281 100644
> --- a/drivers/tty/serial/8250/8250_fsl.c
> +++ b/drivers/tty/serial/8250/8250_fsl.c
> @@ -1,15 +1,12 @@
>  // SPDX-License-Identifier: GPL-2.0
> -#include <linux/serial_reg.h>
> -#include <linux/serial_8250.h>
> -
> -#include "8250.h"
> -
>  /*
>   * Freescale 16550 UART "driver", Copyright (C) 2011 Paul Gortmaker.
> + * Copyright 2020 NXP
> + * Copyright 2020 Puresoftware Ltd.
>   *
>   * This isn't a full driver; it just provides an alternate IRQ
> - * handler to deal with an errata.  Everything else is just
> - * using the bog standard 8250 support.
> + * handler to deal with an errata and provide ACPI wrapper.
> + * Everything else is just using the bog standard 8250 support.
>   *
>   * We follow code flow of serial8250_default_handle_irq() but add
>   * a check for a break and insert a dummy read on the Rx for the @@ -20,6
> +17,16 @@
>   * IRQ event to the next one.
>   */
> 
> +#include <linux/acpi.h>
> +#include <linux/serial_reg.h>
> +#include <linux/serial_8250.h>
> +
> +#include "8250.h"
> +
> +struct fsl8250_data {
> +       int     line;
> +};
> +
>  int fsl8250_handle_irq(struct uart_port *port)  {
>         unsigned char lsr, orig_lsr;
> @@ -79,3 +86,90 @@ int fsl8250_handle_irq(struct uart_port *port)
>         return 1;
>  }
>  EXPORT_SYMBOL_GPL(fsl8250_handle_irq);
> +
> +#ifdef CONFIG_ACPI
> +static int fsl8250_acpi_probe(struct platform_device *pdev) {
> +       struct fsl8250_data *data;
> +       struct uart_8250_port port8250;
> +       struct device *dev = &pdev->dev;
> +       struct resource *regs;
> +
> +       int ret, irq;
> +
> +       regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!regs) {
> +               dev_err(dev, "no registers defined\n");
> +               return -EINVAL;
> +       }
> +
> +       irq = platform_get_irq(pdev, 0);
> +       if (irq < 0) {
> +               if (irq != -EPROBE_DEFER)
> +                       dev_err(dev, "cannot get irq\n");
> +               return irq;
> +       }
> +
> +       memset(&port8250, 0, sizeof(port8250));
> +
> +       ret = device_property_read_u32(dev, "clock-frequency",
> +                                       &port8250.port.uartclk);
> +       if (ret)
> +               return ret;
> +
> +       spin_lock_init(&port8250.port.lock);
> +
> +       port8250.port.mapbase           = regs->start;
> +       port8250.port.irq               = irq;
> +       port8250.port.handle_irq        = fsl8250_handle_irq;
> +       port8250.port.type              = PORT_16550A;
> +       port8250.port.flags             = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF
> +                                               | UPF_FIXED_PORT | UPF_IOREMAP
> +                                               | UPF_FIXED_TYPE;
> +       port8250.port.dev               = dev;
> +       port8250.port.mapsize           = resource_size(regs);
> +       port8250.port.iotype            = UPIO_MEM;
> +       port8250.port.irqflags          = IRQF_SHARED;
> +
> +       port8250.port.membase = devm_ioremap(dev,  port8250.port.mapbase,
> +                                                       port8250.port.mapsize);
> +       if (!port8250.port.membase)
> +               return -ENOMEM;
> +
> +       data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +       if (!data)
> +               return -ENOMEM;
> +
> +       data->line = serial8250_register_8250_port(&port8250);
> +       if (data->line < 0)
> +               ret = data->line;
Would you like to return error here?
> +
> +       platform_set_drvdata(pdev, data);
> +       return 0;
> +}
> +
> +static int fsl8250_acpi_remove(struct platform_device *pdev) {
> +       struct fsl8250_data *data = platform_get_drvdata(pdev);
> +
> +       serial8250_unregister_port(data->line);
> +       return 0;
> +}
> +
> +static const struct acpi_device_id fsl_8250_acpi_id[] = {
> +       { "NXP0018", 0 },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(acpi, fsl_8250_acpi_id);
> +
> +static struct platform_driver fsl8250_platform_driver = {
> +       .driver = {
> +               .name                   = "fsl-16550-uart",
> +               .acpi_match_table       = ACPI_PTR(fsl_8250_acpi_id),
> +       },
> +       .probe                  = fsl8250_acpi_probe,
> +       .remove                 = fsl8250_acpi_remove,
> +};
> +
> +module_platform_driver(fsl8250_platform_driver);
> +#endif
> --
> 2.17.1