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/*
* Copyright (c) 2017 Intel Corporation
*
* Intel Mobile Internet Devices (MID) based on Intel Atom SoCs have few
* microcontrollers inside to do some auxiliary tasks. One of such
* microcontroller is System Controller Unit (SCU) which, in particular,
* is servicing watchdog and controlling system reset function.
*
* This driver enables IPC channel to SCU.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <dm.h>
#include <regmap.h>
#include <syscon.h>
#include <asm/cpu.h>
#include <asm/scu.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/kernel.h>
/* SCU register map */
struct ipc_regs {
u32 cmd;
u32 status;
u32 sptr;
u32 dptr;
u32 reserved[28];
u32 wbuf[4];
u32 rbuf[4];
};
struct scu {
struct ipc_regs *regs;
};
/**
* scu_ipc_send_command() - send command to SCU
* @regs: register map of SCU
* @cmd: command
*
* Command Register (Write Only):
* A write to this register results in an interrupt to the SCU core processor
* Format:
* |rfu2(8) | size(8) | command id(4) | rfu1(3) | ioc(1) | command(8)|
*/
static void scu_ipc_send_command(struct ipc_regs *regs, u32 cmd)
{
writel(cmd, ®s->cmd);
}
/**
* scu_ipc_check_status() - check status of last command
* @regs: register map of SCU
*
* Status Register (Read Only):
* Driver will read this register to get the ready/busy status of the IPC
* block and error status of the IPC command that was just processed by SCU
* Format:
* |rfu3(8)|error code(8)|initiator id(8)|cmd id(4)|rfu1(2)|error(1)|busy(1)|
*/
static int scu_ipc_check_status(struct ipc_regs *regs)
{
int loop_count = 100000;
int status;
do {
status = readl(®s->status);
if (!(status & BIT(0)))
break;
udelay(1);
} while (--loop_count);
if (!loop_count)
return -ETIMEDOUT;
if (status & BIT(1)) {
printf("%s() status=0x%08x\n", __func__, status);
return -EIO;
}
return 0;
}
static int scu_ipc_cmd(struct ipc_regs *regs, u32 cmd, u32 sub,
u32 *in, int inlen, u32 *out, int outlen)
{
int i, err;
for (i = 0; i < inlen; i++)
writel(*in++, ®s->wbuf[i]);
scu_ipc_send_command(regs, (inlen << 16) | (sub << 12) | cmd);
err = scu_ipc_check_status(regs);
if (!err) {
for (i = 0; i < outlen; i++)
*out++ = readl(®s->rbuf[i]);
}
return err;
}
/**
* scu_ipc_simple_command() - send a simple command
* @cmd: command
* @sub: sub type
*
* Issue a simple command to the SCU. Do not use this interface if
* you must then access data as any data values may be overwritten
* by another SCU access by the time this function returns.
*
* This function may sleep. Locking for SCU accesses is handled for
* the caller.
*/
int scu_ipc_simple_command(u32 cmd, u32 sub)
{
struct scu *scu;
struct udevice *dev;
int ret;
ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev);
if (ret)
return ret;
scu = dev_get_priv(dev);
scu_ipc_send_command(scu->regs, sub << 12 | cmd);
return scu_ipc_check_status(scu->regs);
}
int scu_ipc_command(u32 cmd, u32 sub, u32 *in, int inlen, u32 *out, int outlen)
{
struct scu *scu;
struct udevice *dev;
int ret;
ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev);
if (ret)
return ret;
scu = dev_get_priv(dev);
return scu_ipc_cmd(scu->regs, cmd, sub, in, inlen, out, outlen);
}
static int scu_ipc_probe(struct udevice *dev)
{
struct scu *scu = dev_get_priv(dev);
scu->regs = syscon_get_first_range(X86_SYSCON_SCU);
return 0;
}
static const struct udevice_id scu_ipc_match[] = {
{ .compatible = "intel,scu-ipc", .data = X86_SYSCON_SCU },
{ /* sentinel */ }
};
U_BOOT_DRIVER(scu_ipc) = {
.name = "scu_ipc",
.id = UCLASS_SYSCON,
.of_match = scu_ipc_match,
.probe = scu_ipc_probe,
.priv_auto_alloc_size = sizeof(struct scu),
};
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