[PATCH v2 1/4] serial: ns16550: Support run-time configuration
Simon Goldschmidt
simon.k.r.goldschmidt at gmail.com
Mon Dec 9 22:07:14 CET 2019
Am 09.12.2019 um 17:59 schrieb Simon Glass:
> At present this driver uses an assortment of CONFIG options to control
> how it accesses the hardware. This is painful for platforms that are
> supposed to be controlled by a device tree or a previous-stage bootloader.
>
> Add a new CONFIG option to enable fully dynamic configuration. This
> controls register spacing, size, offset and endianness.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v2:
> - runtime -> run-time
> - Enable run-time config for slimbootloader too
> - Improve Kconfig help based on Bin's comments
> - Use ns16550 in patch subject
>
> drivers/serial/Kconfig | 21 +++++++++++++++
> drivers/serial/ns16550.c | 57 ++++++++++++++++++++++++++++++++++------
> include/ns16550.h | 13 +++++++++
> 3 files changed, 83 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> index ece7d87d4c..472a9f0929 100644
> --- a/drivers/serial/Kconfig
> +++ b/drivers/serial/Kconfig
> @@ -598,6 +598,27 @@ config SYS_NS16550
> be used. It can be a constant or a function to get clock, eg,
> get_serial_clock().
>
> +config NS16550_DYNAMIC
> + bool "Allow NS16550 to be configured at runtime"
> + default y if SYS_COREBOOT || SYS_SLIMBOOTLOADER
> + help
> + Enable this option to allow device-tree control of the driver.
> +
> + Normally this driver is controlled by the following options:
> +
> + CONFIG_SYS_NS16550_PORT_MAPPED - indicates that port I/O is used for
> + access. If not enabled, then the UART is memory-mapped.
> + CONFIG_SYS_NS16550_MEM32 - if memory-mapped, indicates that 32-bit
> + access should be used (instead of 8-bit)
> + CONFIG_SYS_NS16550_REG_SIZE - indicates register width and also
> + endianness. If positive, big-endian access is used. If negative,
> + little-endian is used.
> +
> + It is not a good practice for a driver to be statically configured,
> + since it prevents the same driver being used for different types of
> + UARTs in a system. This option avoids this problem at the cost of a
> + slightly increased code size.
> +
> config INTEL_MID_SERIAL
> bool "Intel MID platform UART support"
> depends on DM_SERIAL && OF_CONTROL
> diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
> index 754b6e9921..96c4471efd 100644
> --- a/drivers/serial/ns16550.c
> +++ b/drivers/serial/ns16550.c
> @@ -92,19 +92,57 @@ static inline int serial_in_shift(void *addr, int shift)
> #define CONFIG_SYS_NS16550_CLK 0
> #endif
>
> +static void serial_out_dynamic(struct ns16550_platdata *plat, u8 *addr,
> + int value)
> +{
> + if (plat->flags & NS16550_FLAG_BE) {
> + if (plat->reg_width == 1)
> + writeb(value, addr + (1 << plat->reg_shift) - 1);
> + else if (plat->flags & NS16550_FLAG_IO)
> + out_be32(addr, value);
> + else
> + writel(value, addr);
> + } else {
> + if (plat->reg_width == 1)
> + writeb(value, addr);
> + else if (plat->flags & NS16550_FLAG_IO)
> + out_le32(addr, value);
> + else
> + writel(value, addr);
> + }
> +}
> +
> +static int serial_in_dynamic(struct ns16550_platdata *plat, u8 *addr)
> +{
> + if (plat->flags & NS16550_FLAG_BE) {
> + if (plat->reg_width == 1)
> + return readb(addr + (1 << plat->reg_shift) - 1);
> + else if (plat->flags & NS16550_FLAG_IO)
> + return in_be32(addr);
> + else
> + return readl(addr);
> + } else {
> + if (plat->reg_width == 1)
> + return readb(addr);
> + else if (plat->flags & NS16550_FLAG_IO)
> + return in_le32(addr);
> + else
> + return readl(addr);
> + }
> +}
> +
> static void ns16550_writeb(NS16550_t port, int offset, int value)
> {
> struct ns16550_platdata *plat = port->plat;
> unsigned char *addr;
>
> offset *= 1 << plat->reg_shift;
> - addr = (unsigned char *)plat->base + offset;
> + addr = (unsigned char *)plat->base + offset + plat->reg_offset;
>
> - /*
> - * As far as we know 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_offset, plat->reg_shift, value);
> + if (IS_ENABLED(CONFIG_NS16550_DYNAMIC))
> + serial_out_dynamic(plat, addr, value);
> + else
> + serial_out_shift(addr, plat->reg_shift, value);
> }
>
> static int ns16550_readb(NS16550_t port, int offset)
> @@ -113,9 +151,12 @@ static int ns16550_readb(NS16550_t port, int offset)
> unsigned char *addr;
>
> offset *= 1 << plat->reg_shift;
> - addr = (unsigned char *)plat->base + offset;
> + addr = (unsigned char *)plat->base + offset + plat->reg_offset;
>
> - return serial_in_shift(addr + plat->reg_offset, plat->reg_shift);
> + if (IS_ENABLED(CONFIG_NS16550_DYNAMIC))
> + return serial_in_dynamic(plat, addr);
> + else
> + return serial_in_shift(addr, plat->reg_shift);
> }
>
> static u32 ns16550_getfcr(NS16550_t port)
> diff --git a/include/ns16550.h b/include/ns16550.h
> index 701efeea85..ba9b71962d 100644
> --- a/include/ns16550.h
> +++ b/include/ns16550.h
> @@ -31,6 +31,9 @@
> #define CONFIG_SYS_NS16550_REG_SIZE (-1)
> #endif
>
> +#ifdef CONFIG_NS16550_DYNAMIC
> +#define UART_REG(x) unsigned char x
> +#else
> #if !defined(CONFIG_SYS_NS16550_REG_SIZE) || (CONFIG_SYS_NS16550_REG_SIZE == 0)
> #error "Please define NS16550 registers size."
> #elif defined(CONFIG_SYS_NS16550_MEM32) && !defined(CONFIG_DM_SERIAL)
> @@ -44,6 +47,12 @@
> unsigned char x; \
> unsigned char postpad_##x[-CONFIG_SYS_NS16550_REG_SIZE - 1];
> #endif
> +#endif /* CONFIG_NS16550_DYNAMIC */
> +
> +enum ns16550_flags {
> + NS16550_FLAG_IO = 1 << 0, /* Use I/O access (else mem-mapped) */
> + NS16550_FLAG_BE = 1 << 1, /* Use big-endian access (else little) */
> +};
>
> /**
> * struct ns16550_platdata - information about a NS16550 port
> @@ -51,7 +60,10 @@
> * @base: Base register address
> * @reg_width: IO accesses size of registers (in bytes)
> * @reg_shift: Shift size of registers (0=byte, 1=16bit, 2=32bit...)
> + * @reg_offset: Offset to start of registers
> * @clock: UART base clock speed in Hz
> + * @fcr: Offset of FCR register (normally UART_FCR_DEFVAL)
> + * @flags: A few flags (enum ns16550_flags)
> * @bdf: PCI slot/function (pci_dev_t)
> */
> struct ns16550_platdata {
> @@ -61,6 +73,7 @@ struct ns16550_platdata {
> int reg_offset;
> int clock;
> u32 fcr;
> + int flags;
I'm not too fond of adding 4 bytes here for nothing on most platforms,
but unless you come up with a better idea than cluttering this file with
ifdefs:
Reviewed-by: Simon Goldschmidt <simon.k.r.goldschmidt at gmail.com>
> #if defined(CONFIG_PCI) && defined(CONFIG_SPL)
> int bdf;
> #endif
>
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