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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2022 Ventana Micro Systems Inc.
*/
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <fdtdec.h>
#include <log.h>
#include <watchdog.h>
#include <asm/global_data.h>
#include <asm/io.h>
#include <linux/compiler.h>
#include <serial.h>
#include <linux/err.h>
DECLARE_GLOBAL_DATA_PTR;
#define HTIF_DATA_BITS 48
#define HTIF_DATA_MASK ((1ULL << HTIF_DATA_BITS) - 1)
#define HTIF_DATA_SHIFT 0
#define HTIF_CMD_BITS 8
#define HTIF_CMD_MASK ((1ULL << HTIF_CMD_BITS) - 1)
#define HTIF_CMD_SHIFT 48
#define HTIF_DEV_BITS 8
#define HTIF_DEV_MASK ((1ULL << HTIF_DEV_BITS) - 1)
#define HTIF_DEV_SHIFT 56
#define HTIF_DEV_SYSTEM 0
#define HTIF_DEV_CONSOLE 1
#define HTIF_CONSOLE_CMD_GETC 0
#define HTIF_CONSOLE_CMD_PUTC 1
#if __riscv_xlen == 64
# define TOHOST_CMD(dev, cmd, payload) \
(((u64)(dev) << HTIF_DEV_SHIFT) | \
((u64)(cmd) << HTIF_CMD_SHIFT) | \
(u64)(payload))
#else
# define TOHOST_CMD(dev, cmd, payload) ({ \
if ((dev) || (cmd)) \
__builtin_trap(); \
(payload); })
#endif
#define FROMHOST_DEV(fromhost_value) \
((u64)((fromhost_value) >> HTIF_DEV_SHIFT) & HTIF_DEV_MASK)
#define FROMHOST_CMD(fromhost_value) \
((u64)((fromhost_value) >> HTIF_CMD_SHIFT) & HTIF_CMD_MASK)
#define FROMHOST_DATA(fromhost_value) \
((u64)((fromhost_value) >> HTIF_DATA_SHIFT) & HTIF_DATA_MASK)
struct htif_plat {
void *fromhost;
void *tohost;
int console_char;
};
static void __check_fromhost(struct htif_plat *plat)
{
u64 fh = readq(plat->fromhost);
if (!fh)
return;
writeq(0, plat->fromhost);
/* this should be from the console */
if (FROMHOST_DEV(fh) != HTIF_DEV_CONSOLE)
__builtin_trap();
switch (FROMHOST_CMD(fh)) {
case HTIF_CONSOLE_CMD_GETC:
plat->console_char = 1 + (u8)FROMHOST_DATA(fh);
break;
case HTIF_CONSOLE_CMD_PUTC:
break;
default:
__builtin_trap();
}
}
static void __set_tohost(struct htif_plat *plat,
u64 dev, u64 cmd, u64 data)
{
while (readq(plat->tohost))
__check_fromhost(plat);
writeq(TOHOST_CMD(dev, cmd, data), plat->tohost);
}
static int htif_serial_putc(struct udevice *dev, const char ch)
{
struct htif_plat *plat = dev_get_plat(dev);
__set_tohost(plat, HTIF_DEV_CONSOLE, HTIF_CONSOLE_CMD_PUTC, ch);
return 0;
}
static int htif_serial_getc(struct udevice *dev)
{
int ch;
struct htif_plat *plat = dev_get_plat(dev);
if (plat->console_char < 0)
__check_fromhost(plat);
if (plat->console_char >= 0) {
ch = plat->console_char;
plat->console_char = -1;
__set_tohost(plat, HTIF_DEV_CONSOLE, HTIF_CONSOLE_CMD_GETC, 0);
return (ch) ? ch - 1 : -EAGAIN;
}
return -EAGAIN;
}
static int htif_serial_pending(struct udevice *dev, bool input)
{
struct htif_plat *plat = dev_get_plat(dev);
if (!input)
return 0;
if (plat->console_char < 0)
__check_fromhost(plat);
return (plat->console_char >= 0) ? 1 : 0;
}
static int htif_serial_probe(struct udevice *dev)
{
struct htif_plat *plat = dev_get_plat(dev);
/* Queue first getc request */
__set_tohost(plat, HTIF_DEV_CONSOLE, HTIF_CONSOLE_CMD_GETC, 0);
return 0;
}
static int htif_serial_of_to_plat(struct udevice *dev)
{
fdt_addr_t addr;
struct htif_plat *plat = dev_get_plat(dev);
addr = dev_read_addr_index(dev, 0);
if (addr == FDT_ADDR_T_NONE)
return -ENODEV;
plat->fromhost = (void *)(uintptr_t)addr;
plat->tohost = plat->fromhost + sizeof(u64);
addr = dev_read_addr_index(dev, 1);
if (addr != FDT_ADDR_T_NONE)
plat->tohost = (void *)(uintptr_t)addr;
plat->console_char = -1;
return 0;
}
static const struct dm_serial_ops htif_serial_ops = {
.putc = htif_serial_putc,
.getc = htif_serial_getc,
.pending = htif_serial_pending,
};
static const struct udevice_id htif_serial_ids[] = {
{ .compatible = "ucb,htif0" },
{ }
};
U_BOOT_DRIVER(serial_htif) = {
.name = "serial_htif",
.id = UCLASS_SERIAL,
.of_match = htif_serial_ids,
.of_to_plat = htif_serial_of_to_plat,
.plat_auto = sizeof(struct htif_plat),
.probe = htif_serial_probe,
.ops = &htif_serial_ops,
};
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