[U-Boot] [PATCH 4/9] ns16550: Support I/O accessors selected by DT

[Simon Glass]

Hi Paul,

On 29 January 2016 at 06:54, Paul Burton <paul.burton at imgtec.com> wrote:
> Support making use of I/O accessors for ports when a device tree
> specified an I/O resource. This allows for systems where we have a mix
> of ns16550 ports, some of which should be accessed via I/O ports & some
> of which should be accessed via readb/writeb.
>
> Signed-off-by: Paul Burton <paul.burton at imgtec.com>
> ---
>
>  drivers/serial/ns16550.c | 46 ++++++++++++++++++++++++++++++++++++++--------
>  include/ns16550.h        | 31 ++++++++++++++++++-------------
>  2 files changed, 56 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
> index 93dad33..b1d5319 100644
> --- a/drivers/serial/ns16550.c
> +++ b/drivers/serial/ns16550.c
> @@ -11,6 +11,7 @@
>  #include <ns16550.h>
>  #include <serial.h>
>  #include <watchdog.h>
> +#include <linux/ioport.h>
>  #include <linux/types.h>
>  #include <asm/io.h>
>
> @@ -102,7 +103,7 @@ static void ns16550_writeb(NS16550_t port, int offset, int value)
>         offset *= 1 << plat->reg_shift;
>         addr = map_physmem(plat->base, 0, MAP_NOCACHE) + offset;
>         /*
> -        * As far as we know it doesn't make sense to support selection of
> +        * For many platforms it doesn't make sense to support selection of
>          * these options at run-time, so use the existing CONFIG options.
>          */
>         serial_out_shift(addr, plat->reg_shift, value);
> @@ -119,13 +120,33 @@ static int ns16550_readb(NS16550_t port, int offset)
>         return serial_in_shift(addr, plat->reg_shift);
>  }
>
> +static void ns16550_outb(NS16550_t port, int offset, int value)
> +{
> +       struct ns16550_platdata *plat = port->plat;
> +
> +       offset *= 1 << plat->reg_shift;
> +       outb(value, plat->base + offset);
> +}
> +
> +static int ns16550_inb(NS16550_t port, int offset)
> +{
> +       struct ns16550_platdata *plat = port->plat;
> +
> +       offset *= 1 << plat->reg_shift;
> +       return inb(plat->base + offset);
> +}
> +
>  /* We can clean these up once everything is moved to driver model */
> -#define serial_out(value, addr)        \
> -       ns16550_writeb(com_port, \
> -               (unsigned char *)addr - (unsigned char *)com_port, value)
> -#define serial_in(addr) \
> -       ns16550_readb(com_port, \
> -               (unsigned char *)addr - (unsigned char *)com_port)
> +#define serial_out(value, addr)        do {                                    \
> +       int offset = (unsigned char *)addr - (unsigned char *)com_port; \
> +       com_port->plat->out(com_port, offset, value);                   \

I really don't want to introduce function pointers here. This driver
is a mess but my hope was that when we remove the non-driver-model
code we can clean it up.

I suggest storing the access method in com_port->plat and then using
if() or switch() to select the right one. We can always add #ifdefs to
keep the code size down if it becomes a problem.

> +} while (0)
> +
> +#define serial_in(addr) ({                                             \
> +       int offset = (unsigned char *)addr - (unsigned char *)com_port; \
> +       int value = com_port->plat->in(com_port, offset);               \
> +       value;                                                          \
> +})
>  #endif
>
>  static inline int calc_divisor(NS16550_t port, int clock, int baudrate)
> @@ -365,9 +386,10 @@ int ns16550_serial_ofdata_to_platdata(struct udevice *dev)
>  {
>         struct ns16550_platdata *plat = dev->platdata;
>         fdt_addr_t addr;
> +       unsigned int flags;
>
>         /* try Processor Local Bus device first */
> -       addr = dev_get_addr(dev);
> +       addr = dev_get_addr_flags(dev, &flags);
>  #if defined(CONFIG_PCI) && defined(CONFIG_DM_PCI)
>         if (addr == FDT_ADDR_T_NONE) {
>                 /* then try pci device */
> @@ -400,6 +422,14 @@ int ns16550_serial_ofdata_to_platdata(struct udevice *dev)
>         if (addr == FDT_ADDR_T_NONE)
>                 return -EINVAL;
>
> +       if (flags & IORESOURCE_IO) {
> +               plat->in = ns16550_inb;
> +               plat->out = ns16550_outb;
> +       } else {
> +               plat->in = ns16550_readb;
> +               plat->out = ns16550_writeb;
> +       }
> +
>         plat->base = addr;
>         plat->reg_shift = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
>                                          "reg-shift", 0);
> diff --git a/include/ns16550.h b/include/ns16550.h
> index 4e62067..097f64b 100644
> --- a/include/ns16550.h
> +++ b/include/ns16550.h
> @@ -45,19 +45,6 @@
>         unsigned char postpad_##x[-CONFIG_SYS_NS16550_REG_SIZE - 1];
>  #endif
>
> -/**
> - * struct ns16550_platdata - information about a NS16550 port
> - *
> - * @base:              Base register address
> - * @reg_shift:         Shift size of registers (0=byte, 1=16bit, 2=32bit...)
> - * @clock:             UART base clock speed in Hz
> - */
> -struct ns16550_platdata {
> -       unsigned long base;
> -       int reg_shift;
> -       int clock;
> -};
> -
>  struct udevice;
>
>  struct NS16550 {
> @@ -100,6 +87,24 @@ struct NS16550 {
>
>  typedef struct NS16550 *NS16550_t;
>
> +/**
> + * struct ns16550_platdata - information about a NS16550 port
> + *
> + * @base:              Base register address
> + * @reg_shift:         Shift size of registers (0=byte, 1=16bit, 2=32bit...)
> + * @clock:             UART base clock speed in Hz
> + * @is_io:             Use I/O, not memory, accessors
> + */
> +struct ns16550_platdata {
> +       unsigned long base;
> +       int reg_shift;
> +       int clock;
> +#ifdef CONFIG_DM_SERIAL
> +       int (*in)(NS16550_t port, int offset);
> +       void (*out)(NS16550_t port, int offset, int value);
> +#endif
> +};

Does the above need to move? It would reduce the diff if you left it
in the same place.

> +
>  /*
>   * These are the definitions for the FIFO Control Register
>   */
> --
> 2.7.0
>

Regards,
Simon