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freebsd-skq/sys/dev/uart/uart_dev_mu.c

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/*-
* Copyright (c) 2018 Diane Bruce
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Based on uart_dev_pl011.c
* Copyright (c) 2012 Semihalf.
* All rights reserved.
*/
/*
* The mini Uart has the following features:
* - 7 or 8 bit operation.
* - 1 start and 1 stop bit.
* - No parities.
* - Break generation.
* - 8 symbols deep FIFOs for receive and transmit.
* - SW controlled RTS, SW readable CTS.
* - Auto flow control with programmable FIFO level.
* - 16550 like registers.
* - Baudrate derived from system clock.
* This is a mini UART and it does NOT have the following capabilities:
* - Break detection
* - Framing errors detection.
* - Parity bit
* - Receive Time-out interrupt
* - DCD, DSR, DTR or RI signals.
* The implemented UART is not a 16650 compatible UART However as far
* as possible the first 8 control and status registers are laid out
* like a 16550 UART. All 16550 register bits which are not supported can
* be written but will be ignored and read back as 0. All control bits
* for simple UART receive/transmit operations are available.
*/
#include "opt_acpi.h"
#include "opt_platform.h"
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <machine/bus.h>
#include <machine/machdep.h>
#include <machine/pcpu.h>
#include <dev/uart/uart.h>
#include <dev/uart/uart_cpu.h>
#ifdef FDT
#include <dev/uart/uart_cpu_fdt.h>
#include <dev/ofw/ofw_bus.h>
#endif
#include <dev/uart/uart_bus.h>
#include "uart_if.h"
/* BCM2835 Micro UART registers and masks*/
#define AUX_MU_IO_REG 0x00 /* I/O register */
/*
* According to errata bits 1 and 2 are swapped,
* Also bits 2 and 3 are required to enable interrupts.
*/
#define AUX_MU_IER_REG 0x01
#define IER_RXENABLE (1)
#define IER_TXENABLE (1<<1)
#define IER_REQUIRED (3<<2)
#define IER_MASK_ALL (IER_TXENABLE|IER_RXENABLE)
#define AUX_MU_IIR_REG 0x02
#define IIR_READY (1)
#define IIR_TXREADY (1<<1)
#define IIR_RXREADY (1<<2)
#define IIR_CLEAR (3<<1)
#define AUX_MU_LCR_REG 0x03
#define LCR_WLEN7 (0)
#define LCR_WLEN8 (3)
#define AUX_MU_MCR_REG 0x04
#define AUX_MCR_RTS (1<<1)
#define AUX_MU_LSR_REG 0x05
#define LSR_RXREADY (1)
#define LSR_OVRRUN (1<<1)
#define LSR_TXEMPTY (1<<5)
#define LSR_TXIDLE (1<<6)
#define AUX_MU_MSR_REG 0x06
#define MSR_CTS (1<<5)
#define AUX_MU_SCRATCH_REG 0x07
#define AUX_MU_CNTL_REG 0x08
#define CNTL_RXENAB (1)
#define CNTL_TXENAB (1<<1)
#define AUX_MU_STAT_REG 0x09
#define STAT_TX_SA (1<<1)
#define STAT_RX_SA (1)
#define AUX_MU_BAUD_REG 0x0a
/*
* FIXME: actual register size is SoC-dependent, we need to handle it
*/
#define __uart_getreg(bas, reg) \
bus_space_read_4((bas)->bst, (bas)->bsh, uart_regofs(bas, reg))
#define __uart_setreg(bas, reg, value) \
bus_space_write_4((bas)->bst, (bas)->bsh, uart_regofs(bas, reg), value)
/*
* Low-level UART interface.
*/
static int uart_mu_probe(struct uart_bas *bas);
static void uart_mu_init(struct uart_bas *bas, int, int, int, int);
static void uart_mu_term(struct uart_bas *bas);
static void uart_mu_putc(struct uart_bas *bas, int);
static int uart_mu_rxready(struct uart_bas *bas);
static int uart_mu_getc(struct uart_bas *bas, struct mtx *);
static struct uart_ops uart_mu_ops = {
.probe = uart_mu_probe,
.init = uart_mu_init,
.term = uart_mu_term,
.putc = uart_mu_putc,
.rxready = uart_mu_rxready,
.getc = uart_mu_getc,
};
static int
uart_mu_probe(struct uart_bas *bas)
{
return (0);
}
/*
* According to the docs, the cpu clock is locked to 250Mhz when
* the micro-uart is used
*/
#define CPU_CLOCK 250000000
static void
uart_mu_param(struct uart_bas *bas, int baudrate, int databits, int stopbits,
int parity)
{
uint32_t line;
uint32_t baud;
/*
* Zero all settings to make sure
* UART is disabled and not configured
*/
line = 0x0;
__uart_setreg(bas, AUX_MU_CNTL_REG, line);
/* As I know UART is disabled I can setup the line */
switch (databits) {
case 7:
line |= LCR_WLEN7;
break;
case 6:
case 8:
default:
line |= LCR_WLEN8;
break;
}
__uart_setreg(bas, AUX_MU_LCR_REG, line);
/* See 2.2.1 BCM2835-ARM-Peripherals baudrate */
if (baudrate != 0) {
baud = CPU_CLOCK / (8 * baudrate);
/* XXX
* baud = cpu_clock() / (8 * baudrate);
*/
__uart_setreg(bas, AUX_MU_BAUD_REG, ((uint32_t)(baud & 0xFFFF)));
}
/* re-enable UART */
__uart_setreg(bas, AUX_MU_CNTL_REG, CNTL_RXENAB|CNTL_TXENAB);
}
static void
uart_mu_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
int parity)
{
/* Mask all interrupts */
__uart_setreg(bas, AUX_MU_IER_REG, 0);
uart_mu_param(bas, baudrate, databits, stopbits, parity);
}
static void
uart_mu_term(struct uart_bas *bas)
{
}
static void
uart_mu_putc(struct uart_bas *bas, int c)
{
/* Wait when TX FIFO full. Push character otherwise. */
while ((__uart_getreg(bas, AUX_MU_LSR_REG) & LSR_TXEMPTY) == 0)
;
__uart_setreg(bas, AUX_MU_IO_REG, c & 0xff);
}
static int
uart_mu_rxready(struct uart_bas *bas)
{
return ((__uart_getreg(bas, AUX_MU_LSR_REG) & LSR_RXREADY) != 0);
}
static int
uart_mu_getc(struct uart_bas *bas, struct mtx *hwmtx)
{
int c;
while(!uart_mu_rxready(bas))
;
c = __uart_getreg(bas, AUX_MU_IO_REG) & 0xff;
return (c);
}
/*
* High-level UART interface.
*/
struct uart_mu_softc {
struct uart_softc bas;
uint16_t aux_ier; /* Interrupt mask */
};
static int uart_mu_bus_attach(struct uart_softc *);
static int uart_mu_bus_detach(struct uart_softc *);
static int uart_mu_bus_flush(struct uart_softc *, int);
static int uart_mu_bus_getsig(struct uart_softc *);
static int uart_mu_bus_ioctl(struct uart_softc *, int, intptr_t);
static int uart_mu_bus_ipend(struct uart_softc *);
static int uart_mu_bus_param(struct uart_softc *, int, int, int, int);
static int uart_mu_bus_probe(struct uart_softc *);
static int uart_mu_bus_receive(struct uart_softc *);
static int uart_mu_bus_setsig(struct uart_softc *, int);
static int uart_mu_bus_transmit(struct uart_softc *);
static void uart_mu_bus_grab(struct uart_softc *);
static void uart_mu_bus_ungrab(struct uart_softc *);
static kobj_method_t uart_mu_methods[] = {
KOBJMETHOD(uart_attach, uart_mu_bus_attach),
KOBJMETHOD(uart_detach, uart_mu_bus_detach),
KOBJMETHOD(uart_flush, uart_mu_bus_flush),
KOBJMETHOD(uart_getsig, uart_mu_bus_getsig),
KOBJMETHOD(uart_ioctl, uart_mu_bus_ioctl),
KOBJMETHOD(uart_ipend, uart_mu_bus_ipend),
KOBJMETHOD(uart_param, uart_mu_bus_param),
KOBJMETHOD(uart_probe, uart_mu_bus_probe),
KOBJMETHOD(uart_receive, uart_mu_bus_receive),
KOBJMETHOD(uart_setsig, uart_mu_bus_setsig),
KOBJMETHOD(uart_transmit, uart_mu_bus_transmit),
KOBJMETHOD(uart_grab, uart_mu_bus_grab),
KOBJMETHOD(uart_ungrab, uart_mu_bus_ungrab),
{ 0, 0 }
};
static struct uart_class uart_mu_class = {
"aux-uart",
uart_mu_methods,
sizeof(struct uart_mu_softc),
.uc_ops = &uart_mu_ops,
.uc_range = 0x48,
.uc_rclk = 0,
.uc_rshift = 2
};
#ifdef FDT
static struct ofw_compat_data fdt_compat_data[] = {
{"brcm,bcm2835-aux-uart" , (uintptr_t)&uart_mu_class},
{NULL, (uintptr_t)NULL},
};
UART_FDT_CLASS_AND_DEVICE(fdt_compat_data);
#endif
static int
uart_mu_bus_attach(struct uart_softc *sc)
{
struct uart_mu_softc *psc;
struct uart_bas *bas;
psc = (struct uart_mu_softc *)sc;
bas = &sc->sc_bas;
/* Clear interrupts */
__uart_setreg(bas, AUX_MU_IIR_REG, IIR_CLEAR);
/* Enable interrupts */
psc->aux_ier = (IER_RXENABLE|IER_TXENABLE|IER_REQUIRED);
__uart_setreg(bas, AUX_MU_IER_REG, psc->aux_ier);
sc->sc_txbusy = 0;
return (0);
}
static int
uart_mu_bus_detach(struct uart_softc *sc)
{
return (0);
}
static int
uart_mu_bus_flush(struct uart_softc *sc, int what)
{
return (0);
}
static int
uart_mu_bus_getsig(struct uart_softc *sc)
{
return (0);
}
static int
uart_mu_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
{
struct uart_bas *bas;
int error;
bas = &sc->sc_bas;
error = 0;
uart_lock(sc->sc_hwmtx);
switch (request) {
case UART_IOCTL_BREAK:
break;
case UART_IOCTL_BAUD:
*(int*)data = 115200;
break;
default:
error = EINVAL;
break;
}
uart_unlock(sc->sc_hwmtx);
return (error);
}
static int
uart_mu_bus_ipend(struct uart_softc *sc)
{
struct uart_mu_softc *psc;
struct uart_bas *bas;
uint32_t ints;
int ipend;
psc = (struct uart_mu_softc *)sc;
bas = &sc->sc_bas;
uart_lock(sc->sc_hwmtx);
ints = __uart_getreg(bas, AUX_MU_IIR_REG);
ipend = 0;
/*
* According to docs only one of IIR_RXREADY
* or IIR_TXREADY are valid eg. Only one or the other.
*/
if (ints & IIR_RXREADY) {
ipend |= SER_INT_RXREADY;
} else if (ints & IIR_TXREADY) {
if (__uart_getreg(bas, AUX_MU_LSR_REG) & LSR_TXIDLE) {
if (sc->sc_txbusy)
ipend |= SER_INT_TXIDLE;
/* Disable TX interrupt */
__uart_setreg(bas, AUX_MU_IER_REG,
psc->aux_ier & ~IER_TXENABLE);
}
}
uart_unlock(sc->sc_hwmtx);
return (ipend);
}
static int
uart_mu_bus_param(struct uart_softc *sc, int baudrate, int databits,
int stopbits, int parity)
{
uart_lock(sc->sc_hwmtx);
uart_mu_param(&sc->sc_bas, baudrate, databits, stopbits, parity);
uart_unlock(sc->sc_hwmtx);
return (0);
}
static int
uart_mu_bus_probe(struct uart_softc *sc)
{
/* MU always has 8 byte deep fifo */
sc->sc_rxfifosz = 8;
sc->sc_txfifosz = 8;
device_set_desc(sc->sc_dev, "BCM2835 Mini-UART");
return (0);
}
static int
uart_mu_bus_receive(struct uart_softc *sc)
{
struct uart_mu_softc *psc;
struct uart_bas *bas;
uint32_t lsr, xc;
int rx;
bas = &sc->sc_bas;
uart_lock(sc->sc_hwmtx);
psc = (struct uart_mu_softc *)sc;
lsr = __uart_getreg(bas, AUX_MU_LSR_REG);
while (lsr & LSR_RXREADY) {
xc = __uart_getreg(bas, AUX_MU_IO_REG);
rx = xc & 0xff;
if (uart_rx_full(sc)) {
sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
break;
}
uart_rx_put(sc, rx);
lsr = __uart_getreg(bas, AUX_MU_LSR_REG);
}
uart_unlock(sc->sc_hwmtx);
return (0);
}
static int
uart_mu_bus_setsig(struct uart_softc *sc, int sig)
{
return (0);
}
static int
uart_mu_bus_transmit(struct uart_softc *sc)
{
struct uart_mu_softc *psc;
struct uart_bas *bas;
int i;
psc = (struct uart_mu_softc *)sc;
bas = &sc->sc_bas;
uart_lock(sc->sc_hwmtx);
for (i = 0; i < sc->sc_txdatasz; i++) {
__uart_setreg(bas, AUX_MU_IO_REG, sc->sc_txbuf[i] & 0xff);
uart_barrier(bas);
}
/* Mark busy and enable TX interrupt */
sc->sc_txbusy = 1;
__uart_setreg(bas, AUX_MU_IER_REG, psc->aux_ier);
uart_unlock(sc->sc_hwmtx);
return (0);
}
static void
uart_mu_bus_grab(struct uart_softc *sc)
{
struct uart_mu_softc *psc;
struct uart_bas *bas;
psc = (struct uart_mu_softc *)sc;
bas = &sc->sc_bas;
/* Disable interrupts on switch to polling */
uart_lock(sc->sc_hwmtx);
__uart_setreg(bas, AUX_MU_IER_REG, psc->aux_ier &~IER_MASK_ALL);
uart_unlock(sc->sc_hwmtx);
}
static void
uart_mu_bus_ungrab(struct uart_softc *sc)
{
struct uart_mu_softc *psc;
struct uart_bas *bas;
psc = (struct uart_mu_softc *)sc;
bas = &sc->sc_bas;
/* Switch to using interrupts while not grabbed */
uart_lock(sc->sc_hwmtx);
__uart_setreg(bas, AUX_MU_CNTL_REG, CNTL_RXENAB|CNTL_TXENAB);
__uart_setreg(bas, AUX_MU_IER_REG, psc->aux_ier);
uart_unlock(sc->sc_hwmtx);
}
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