diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_rsa.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_rsa.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_rsa.c b/drivers/tty/serial/8250/8250_rsa.c new file mode 100644 index 000000000000..fff9395948e3 --- /dev/null +++ b/drivers/tty/serial/8250/8250_rsa.c @@ -0,0 +1,211 @@ +// SPDX-License-Identifier: GPL-2.0+ + +#include <linux/errno.h> +#include <linux/ioport.h> +#include <linux/module.h> +#include <linux/moduleparam.h> + +#include <linux/serial.h> +#include <linux/serial_8250.h> + +#include "8250.h" + +#define PORT_RSA_MAX 4 +static unsigned long probe_rsa[PORT_RSA_MAX]; +static unsigned int probe_rsa_count; + +static const struct uart_ops *core_port_base_ops; + +static int rsa8250_request_resource(struct uart_8250_port *up) +{ + struct uart_port *port = &up->port; + unsigned long start = UART_RSA_BASE << port->regshift; + unsigned int size = 8 << port->regshift; + + switch (port->iotype) { + case UPIO_HUB6: + case UPIO_PORT: + start += port->iobase; + if (!request_region(start, size, "serial-rsa")) + return -EBUSY; + return 0; + default: + return -EINVAL; + } +} + +static void rsa8250_release_resource(struct uart_8250_port *up) +{ + struct uart_port *port = &up->port; + unsigned long offset = UART_RSA_BASE << port->regshift; + unsigned int size = 8 << port->regshift; + + switch (port->iotype) { + case UPIO_HUB6: + case UPIO_PORT: + release_region(port->iobase + offset, size); + break; + default: + break; + } +} + +static void univ8250_config_port(struct uart_port *port, int flags) +{ + struct uart_8250_port *up = up_to_u8250p(port); + unsigned int i; + + up->probe &= ~UART_PROBE_RSA; + if (port->type == PORT_RSA) { + if (rsa8250_request_resource(up) == 0) + up->probe |= UART_PROBE_RSA; + } else if (flags & UART_CONFIG_TYPE) { + for (i = 0; i < probe_rsa_count; i++) { + if (probe_rsa[i] == up->port.iobase) { + if (rsa8250_request_resource(up) == 0) + up->probe |= UART_PROBE_RSA; + break; + } + } + } + + core_port_base_ops->config_port(port, flags); + + if (port->type != PORT_RSA && up->probe & UART_PROBE_RSA) + rsa8250_release_resource(up); +} + +static int univ8250_request_port(struct uart_port *port) +{ + struct uart_8250_port *up = up_to_u8250p(port); + int ret; + + ret = core_port_base_ops->request_port(port); + if (ret == 0 && port->type == PORT_RSA) { + ret = rsa8250_request_resource(up); + if (ret < 0) + core_port_base_ops->release_port(port); + } + + return ret; +} + +static void univ8250_release_port(struct uart_port *port) +{ + struct uart_8250_port *up = up_to_u8250p(port); + + if (port->type == PORT_RSA) + rsa8250_release_resource(up); + core_port_base_ops->release_port(port); +} + +/* + * It is not allowed to directly reference any symbols from 8250.ko here as + * that would result in a dependency loop between the 8250.ko and + * 8250_base.ko modules. This function is called from 8250.ko and is used to + * break the symbolic dependency cycle. Anything that is needed from 8250.ko + * has to be passed as pointers to this function which then can adjust those + * variables on 8250.ko side or store them locally as needed. + */ +void univ8250_rsa_support(struct uart_ops *ops, const struct uart_ops *core_ops) +{ + core_port_base_ops = core_ops; + ops->config_port = univ8250_config_port; + ops->request_port = univ8250_request_port; + ops->release_port = univ8250_release_port; +} +EXPORT_SYMBOL_FOR_MODULES(univ8250_rsa_support, "8250"); + +module_param_hw_array(probe_rsa, ulong, ioport, &probe_rsa_count, 0444); +MODULE_PARM_DESC(probe_rsa, "Probe I/O ports for RSA"); + +/* + * Attempts to turn on the RSA FIFO. Returns zero on failure. + * We set the port uart clock rate if we succeed. + */ +static int __rsa_enable(struct uart_8250_port *up) +{ + unsigned char mode; + int result; + + mode = serial_in(up, UART_RSA_MSR); + result = mode & UART_RSA_MSR_FIFO; + + if (!result) { + serial_out(up, UART_RSA_MSR, mode | UART_RSA_MSR_FIFO); + mode = serial_in(up, UART_RSA_MSR); + result = mode & UART_RSA_MSR_FIFO; + } + + if (result) + up->port.uartclk = SERIAL_RSA_BAUD_BASE * 16; + + return result; +} + +/* + * If this is an RSA port, see if we can kick it up to the higher speed clock. + */ +void rsa_enable(struct uart_8250_port *up) +{ + if (up->port.type != PORT_RSA) + return; + + if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16) { + guard(uart_port_lock_irq)(&up->port); + __rsa_enable(up); + } + if (up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16) + serial_out(up, UART_RSA_FRR, 0); +} + +/* + * Attempts to turn off the RSA FIFO and resets the RSA board back to 115kbps compat mode. It is + * unknown why interrupts were disabled in here. However, the caller is expected to preserve this + * behaviour by grabbing the spinlock before calling this function. + */ +void rsa_disable(struct uart_8250_port *up) +{ + unsigned char mode; + int result; + + if (up->port.type != PORT_RSA) + return; + + if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16) + return; + + guard(uart_port_lock_irq)(&up->port); + + mode = serial_in(up, UART_RSA_MSR); + result = !(mode & UART_RSA_MSR_FIFO); + + if (!result) { + serial_out(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO); + mode = serial_in(up, UART_RSA_MSR); + result = !(mode & UART_RSA_MSR_FIFO); + } + + if (result) + up->port.uartclk = SERIAL_RSA_BAUD_BASE_LO * 16; +} + +void rsa_autoconfig(struct uart_8250_port *up) +{ + /* Only probe for RSA ports if we got the region. */ + if (up->port.type != PORT_16550A) + return; + if (!(up->probe & UART_PROBE_RSA)) + return; + + if (__rsa_enable(up)) + up->port.type = PORT_RSA; +} + +void rsa_reset(struct uart_8250_port *up) +{ + if (up->port.type != PORT_RSA) + return; + + serial_out(up, UART_RSA_FRR, 0); +} |