WSL2-Linux-Kernel/arch/mips/generic/board-sead3.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2016 Imagination Technologies
 * Author: Paul Burton <paul.burton@mips.com>
 */

#define pr_fmt(fmt) "sead3: " fmt

#include <linux/errno.h>
#include <linux/libfdt.h>
#include <linux/printk.h>
#include <linux/sizes.h>

#include <asm/fw/fw.h>
#include <asm/io.h>
#include <asm/machine.h>
#include <asm/yamon-dt.h>

#define SEAD_CONFIG			CKSEG1ADDR(0x1b100110)
#define SEAD_CONFIG_GIC_PRESENT		BIT(1)

#define MIPS_REVISION			CKSEG1ADDR(0x1fc00010)
#define MIPS_REVISION_MACHINE		(0xf << 4)
#define MIPS_REVISION_MACHINE_SEAD3	(0x4 << 4)

/*
 * Maximum 384MB RAM at physical address 0, preceding any I/O.
 */
static struct yamon_mem_region mem_regions[] __initdata = {
	/* start	size */
	{ 0,		SZ_256M + SZ_128M },
	{}
};

static __init bool sead3_detect(void)
{
	uint32_t rev;

	rev = __raw_readl((void *)MIPS_REVISION);
	return (rev & MIPS_REVISION_MACHINE) == MIPS_REVISION_MACHINE_SEAD3;
}

static __init int append_memory(void *fdt)
{
	return yamon_dt_append_memory(fdt, mem_regions);
}

static __init int remove_gic(void *fdt)
{
	const unsigned int cpu_ehci_int = 2;
	const unsigned int cpu_uart_int = 4;
	const unsigned int cpu_eth_int = 6;
	int gic_off, cpu_off, uart_off, eth_off, ehci_off, err;
	uint32_t cfg, cpu_phandle;

	/* leave the GIC node intact if a GIC is present */
	cfg = __raw_readl((uint32_t *)SEAD_CONFIG);
	if (cfg & SEAD_CONFIG_GIC_PRESENT)
		return 0;

	gic_off = fdt_node_offset_by_compatible(fdt, -1, "mti,gic");
	if (gic_off < 0) {
		pr_err("unable to find DT GIC node: %d\n", gic_off);
		return gic_off;
	}

	err = fdt_nop_node(fdt, gic_off);
	if (err) {
		pr_err("unable to nop GIC node\n");
		return err;
	}

	cpu_off = fdt_node_offset_by_compatible(fdt, -1,
			"mti,cpu-interrupt-controller");
	if (cpu_off < 0) {
		pr_err("unable to find CPU intc node: %d\n", cpu_off);
		return cpu_off;
	}

	cpu_phandle = fdt_get_phandle(fdt, cpu_off);
	if (!cpu_phandle) {
		pr_err("unable to get CPU intc phandle\n");
		return -EINVAL;
	}

	uart_off = fdt_node_offset_by_compatible(fdt, -1, "ns16550a");
	while (uart_off >= 0) {
		err = fdt_setprop_u32(fdt, uart_off, "interrupt-parent",
				      cpu_phandle);
		if (err) {
			pr_warn("unable to set UART interrupt-parent: %d\n",
				err);
			return err;
		}

		err = fdt_setprop_u32(fdt, uart_off, "interrupts",
				      cpu_uart_int);
		if (err) {
			pr_err("unable to set UART interrupts property: %d\n",
			       err);
			return err;
		}

		uart_off = fdt_node_offset_by_compatible(fdt, uart_off,
							 "ns16550a");
	}
	if (uart_off != -FDT_ERR_NOTFOUND) {
		pr_err("error searching for UART DT node: %d\n", uart_off);
		return uart_off;
	}

	eth_off = fdt_node_offset_by_compatible(fdt, -1, "smsc,lan9115");
	if (eth_off < 0) {
		pr_err("unable to find ethernet DT node: %d\n", eth_off);
		return eth_off;
	}

	err = fdt_setprop_u32(fdt, eth_off, "interrupt-parent", cpu_phandle);
	if (err) {
		pr_err("unable to set ethernet interrupt-parent: %d\n", err);
		return err;
	}

	err = fdt_setprop_u32(fdt, eth_off, "interrupts", cpu_eth_int);
	if (err) {
		pr_err("unable to set ethernet interrupts property: %d\n", err);
		return err;
	}

	ehci_off = fdt_node_offset_by_compatible(fdt, -1, "generic-ehci");
	if (ehci_off < 0) {
		pr_err("unable to find EHCI DT node: %d\n", ehci_off);
		return ehci_off;
	}

	err = fdt_setprop_u32(fdt, ehci_off, "interrupt-parent", cpu_phandle);
	if (err) {
		pr_err("unable to set EHCI interrupt-parent: %d\n", err);
		return err;
	}

	err = fdt_setprop_u32(fdt, ehci_off, "interrupts", cpu_ehci_int);
	if (err) {
		pr_err("unable to set EHCI interrupts property: %d\n", err);
		return err;
	}

	return 0;
}

static const struct mips_fdt_fixup sead3_fdt_fixups[] __initconst = {
	{ yamon_dt_append_cmdline, "append command line" },
	{ append_memory, "append memory" },
	{ remove_gic, "remove GIC when not present" },
	{ yamon_dt_serial_config, "append serial configuration" },
	{ },
};

static __init const void *sead3_fixup_fdt(const void *fdt,
					  const void *match_data)
{
	static unsigned char fdt_buf[16 << 10] __initdata;
	int err;

	if (fdt_check_header(fdt))
		panic("Corrupt DT");

	/* if this isn't SEAD3, something went wrong */
	BUG_ON(fdt_node_check_compatible(fdt, 0, "mti,sead-3"));

	fw_init_cmdline();

	err = apply_mips_fdt_fixups(fdt_buf, sizeof(fdt_buf),
				    fdt, sead3_fdt_fixups);
	if (err)
		panic("Unable to fixup FDT: %d", err);

	return fdt_buf;
}

static __init unsigned int sead3_measure_hpt_freq(void)
{
	void __iomem *status_reg = (void __iomem *)0xbf000410;
	unsigned int freq, orig, tick = 0;
	unsigned long flags;

	local_irq_save(flags);

	orig = readl(status_reg) & 0x2;		      /* get original sample */
	/* wait for transition */
	while ((readl(status_reg) & 0x2) == orig)
		;
	orig = orig ^ 0x2;			      /* flip the bit */

	write_c0_count(0);

	/* wait 1 second (the sampling clock transitions every 10ms) */
	while (tick < 100) {
		/* wait for transition */
		while ((readl(status_reg) & 0x2) == orig)
			;
		orig = orig ^ 0x2;			      /* flip the bit */
		tick++;
	}

	freq = read_c0_count();

	local_irq_restore(flags);

	return freq;
}

extern char __dtb_sead3_begin[];

MIPS_MACHINE(sead3) = {
	.fdt = __dtb_sead3_begin,
	.detect = sead3_detect,
	.fixup_fdt = sead3_fixup_fdt,
	.measure_hpt_freq = sead3_measure_hpt_freq,
};