On Fri, 19 Mar 2021 09:07:26 +1100
Benjamin Herrenschmidt <b...@kernel.crashing.org> wrote:
> This adds the ability for the driver to access UARTs via MMIO instead
> of PIO selectively at runtime, and exposes a new function to add an
> MMIO port.
>
> Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> ---
> docs/grub.texi | 3 +-
> grub-core/term/ns8250.c | 78
> ++++++++++++++++++++++++++++++++--------- grub-core/term/serial.c |
> 22 ++++++++++-- include/grub/serial.h | 10 +++++-
> 4 files changed, 92 insertions(+), 21 deletions(-)
>
> diff --git a/docs/grub.texi b/docs/grub.texi
> index eeb3118eb..4a3287119 100644
> --- a/docs/grub.texi
> +++ b/docs/grub.texi
> @@ -3878,7 +3878,8 @@ Commands usable anywhere in the menu and in the
> command-line. Initialize a serial device. @var{unit} is a number in
> the range 0-3 specifying which serial port to use; default is 0,
> which corresponds to the port often called COM1. @var{port} is the
> I/O port where the UART
Perhaps instead of
"@var{port} is the I/O port where the UART is to be found"
it should be changed to
"@var{port} is the I/O port or MMIO address where the UART is to be
found"
> -is to be found; if specified it takes precedence over @var{unit}.
> +is to be found; if specified it takes precedence over @var{unit}. It
>can
> +also be ``mmio'' followed by the MMIO address of the port in
> hexadecimal.
This was unclear to me without reading the source. "It can also be
``mmio''" -- perhaps "It" should be "The port argument can also be an
MMIO address in hexadecimal prefixed by ``mmio''".
Or if the change in my first comment is made the whole sentence could
instead read:
"The form of the MMIO address port argument is ``mmio'' followed by
the MMIO address in hexadecimal."
> @var{speed} is the
> transmission speed; default is 9600. @var{word} and @var{stop} are
> the number of data bits and stop bits. Data bits must be in the range
> 5-8 and stop bits must be 1 or 2. Default is 8 data diff --git
> a/grub-core/term/ns8250.c b/grub-core/term/ns8250.c index
> 39809d042..183e14b3b 100644 --- a/grub-core/term/ns8250.c
> +++ b/grub-core/term/ns8250.c
> @@ -44,6 +44,24 @@ static int dead_ports = 0;
> #define DEFAULT_BASE_CLOCK 115200
> #endif
>
> +static inline unsigned char
> +ns8250_reg_read (struct grub_serial_port *port, grub_addr_t reg)
> +{
> + asm volatile("" : : : "memory");
> + if (port->mmio)
> + return *((volatile unsigned char *)(port->mmio_base + reg));
> + return grub_inb (port->port + reg);
> +}
> +
> +static inline void
> +ns8250_reg_write (struct grub_serial_port *port, unsigned char
> value, grub_addr_t reg) +{
> + asm volatile("" : : : "memory");
> + if (port->mmio)
> + *((volatile char *)(port->mmio_base + reg)) = value;
> + else
> + grub_outb (value, port->port + reg);
> +}
>
> /* Convert speed to divisor. */
> static unsigned short
> @@ -94,43 +112,42 @@ do_real_config (struct grub_serial_port *port)
> divisor = serial_get_divisor (port, &port->config);
>
> /* Turn off the interrupt. */
> - grub_outb (0, port->port + UART_IER);
> + ns8250_reg_write (port, 0, UART_IER);
>
> /* Set DLAB. */
> - grub_outb (UART_DLAB, port->port + UART_LCR);
> + ns8250_reg_write (port, UART_DLAB, UART_LCR);
>
> - /* Set the baud rate. */
> - grub_outb (divisor & 0xFF, port->port + UART_DLL);
> - grub_outb (divisor >> 8, port->port + UART_DLH);
> + ns8250_reg_write (port, divisor & 0xFF, UART_DLL);
> + ns8250_reg_write (port, divisor >> 8, UART_DLH);
>
> /* Set the line status. */
> status |= (parities[port->config.parity]
> | (port->config.word_len - 5)
> | stop_bits[port->config.stop_bits]);
> - grub_outb (status, port->port + UART_LCR);
> + ns8250_reg_write (port, status, UART_LCR);
>
> if (port->config.rtscts)
> {
> /* Enable the FIFO. */
> - grub_outb (UART_ENABLE_FIFO_TRIGGER1, port->port + UART_FCR);
> + ns8250_reg_write (port, UART_ENABLE_FIFO_TRIGGER1, UART_FCR);
>
> /* Turn on DTR and RTS. */
> - grub_outb (UART_ENABLE_DTRRTS, port->port + UART_MCR);
> + ns8250_reg_write (port, UART_ENABLE_DTRRTS, UART_MCR);
> }
> else
> {
> /* Enable the FIFO. */
> - grub_outb (UART_ENABLE_FIFO_TRIGGER14, port->port + UART_FCR);
> + ns8250_reg_write (port, UART_ENABLE_FIFO_TRIGGER14, UART_FCR);
>
> /* Turn on DTR, RTS, and OUT2. */
> - grub_outb (UART_ENABLE_DTRRTS | UART_ENABLE_OUT2, port->port +
> UART_MCR);
> + ns8250_reg_write (port, UART_ENABLE_DTRRTS | UART_ENABLE_OUT2,
> UART_MCR); }
>
> /* Drain the input buffer. */
> endtime = grub_get_time_ms () + 1000;
> - while (grub_inb (port->port + UART_LSR) & UART_DATA_READY)
> + while (ns8250_reg_read (port, UART_LSR) & UART_DATA_READY)
> {
> - grub_inb (port->port + UART_RX);
> + ns8250_reg_read (port, UART_RX);
> if (grub_get_time_ms () > endtime)
> {
> port->broken = 1;
> @@ -146,8 +163,8 @@ static int
> serial_hw_fetch (struct grub_serial_port *port)
> {
> do_real_config (port);
> - if (grub_inb (port->port + UART_LSR) & UART_DATA_READY)
> - return grub_inb (port->port + UART_RX);
> + if (ns8250_reg_read (port, UART_LSR) & UART_DATA_READY)
> + return ns8250_reg_read (port, UART_RX);
>
> return -1;
> }
> @@ -167,7 +184,7 @@ serial_hw_put (struct grub_serial_port *port,
> const int c) else
> endtime = grub_get_time_ms () + 200;
> /* Wait until the transmitter holding register is empty. */
> - while ((grub_inb (port->port + UART_LSR) & UART_EMPTY_TRANSMITTER)
> == 0)
> + while ((ns8250_reg_read (port, UART_LSR) & UART_EMPTY_TRANSMITTER)
> == 0) {
> if (grub_get_time_ms () > endtime)
> {
> @@ -180,7 +197,7 @@ serial_hw_put (struct grub_serial_port *port,
> const int c) if (port->broken)
> port->broken--;
>
> - grub_outb (c, port->port + UART_TX);
> + ns8250_reg_write (port, c, UART_TX);
> }
>
> /* Initialize a serial device. PORT is the port number for a serial
> device. @@ -260,6 +277,7 @@ grub_ns8250_init (void)
> com_ports[i].name = com_names[i];
> com_ports[i].driver = &grub_ns8250_driver;
> com_ports[i].port = serial_hw_io_addr[i];
> + com_ports[i].mmio = 0;
> err = grub_serial_config_defaults (&com_ports[i]);
> if (err)
> grub_print_error ();
> @@ -311,8 +329,36 @@ grub_serial_ns8250_add_port (grub_port_t port)
> }
> p->driver = &grub_ns8250_driver;
> grub_serial_config_defaults (p);
> + p->mmio = 0;
> p->port = port;
> grub_serial_register (p);
>
> return p->name;
> }
> +
> +char *
> +grub_serial_ns8250_add_mmio(grub_addr_t addr)
> +{
> + struct grub_serial_port *p;
> + unsigned i;
> + for (i = 0; i < GRUB_SERIAL_PORT_NUM; i++)
> + if (com_ports[i].mmio && com_ports[i].mmio_base == addr)
> + return com_names[i];
> +
> + p = grub_malloc (sizeof (*p));
> + if (!p)
> + return NULL;
> + p->name = grub_xasprintf ("mmio%llx", (unsigned long long) addr);
> + if (!p->name)
> + {
> + grub_free (p);
> + return NULL;
> + }
> + p->driver = &grub_ns8250_driver;
> + grub_serial_config_defaults (p);
> + p->mmio = 1;
> + p->mmio_base = addr;
> + grub_serial_register (p);
> +
> + return p->name;
> +}
> diff --git a/grub-core/term/serial.c b/grub-core/term/serial.c
> index f9271b092..7d4dbb2de 100644
> --- a/grub-core/term/serial.c
> +++ b/grub-core/term/serial.c
> @@ -160,6 +160,18 @@ grub_serial_find (const char *name)
> if (!name)
> return NULL;
>
> + FOR_SERIAL_PORTS (port)
> + if (grub_strcmp (port->name, name) == 0)
> + break;
> + }
> + if (!port && grub_memcmp (name, "mmio", sizeof ("mmio") - 1) == 0
> + && grub_isxdigit (name [sizeof ("mmio") - 1]))
It would look nicer if the prefix were "mmio:" to more clearly mark it
as a prefix.
> + {
> + name = grub_serial_ns8250_add_mmio (grub_strtoul (&name[sizeof
> ("mmio") - 1],
> + 0, 16),
> NULL);
> + if (!name)
> + return NULL;
> +
> FOR_SERIAL_PORTS (port)
> if (grub_strcmp (port->name, name) == 0)
> break;
> @@ -195,14 +207,18 @@ grub_cmd_serial (grub_extcmd_context_t ctxt,
> int argc, char **args) if (state[OPTION_UNIT].set)
> {
> grub_snprintf (pname, sizeof (pname), "com%ld",
> - grub_strtoul (state[0].arg, 0, 0));
> + grub_strtoul (state[OPTION_UNIT].arg, 0, 0));
> name = pname;
> }
>
> if (state[OPTION_PORT].set)
> {
> - grub_snprintf (pname, sizeof (pname), "port%lx",
> - grub_strtoul (state[1].arg, 0, 0));
> + if (grub_memcmp (state[OPTION_PORT].arg, "mmio", 4) == 0)
> + grub_snprintf(pname, sizeof (pname), "%s",
> state[OPTION_PORT].arg);
> + else
> + grub_snprintf (pname, sizeof (pname), "port%lx",
> + grub_strtoul (state[OPTION_PORT].arg, 0,
> 0)); +
> name = pname;
> }
>
> diff --git a/include/grub/serial.h b/include/grub/serial.h
> index 67379de45..a5756cd25 100644
> --- a/include/grub/serial.h
> +++ b/include/grub/serial.h
> @@ -86,9 +86,16 @@ struct grub_serial_port
> */
> union
> {
> + struct
> + {
> + int mmio;
> + union {
> #if defined(__mips__) || defined (__i386__) || defined (__x86_64__)
> - grub_port_t port;
> + grub_port_t port;
> #endif
> + grub_addr_t mmio_base;
> + };
> + };
> struct
> {
> grub_usb_device_t usbdev;
> @@ -178,6 +185,7 @@ grub_serial_config_defaults (struct
> grub_serial_port *port) #if defined(__mips__) || defined (__i386__)
> || defined (__x86_64__) void grub_ns8250_init (void);
> char *grub_serial_ns8250_add_port (grub_port_t port);
> +char *grub_serial_ns8250_add_mmio(grub_addr_t addr);
> #endif
> #ifdef GRUB_MACHINE_IEEE1275
> void grub_ofserial_init (void);
Glenn
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