board-ocelot.c

 1// SPDX-License-Identifier: (GPL-2.0 OR MIT)
 2/*
 3 * Microsemi MIPS SoC support
 4 *
 5 * Copyright (c) 2017 Microsemi Corporation
 6 */
 7#include <linux/string.h>
 8#include <asm/machine.h>
 9#include <asm/prom.h>
10
11#define DEVCPU_GCB_CHIP_REGS_CHIP_ID	0x71070000
12#define CHIP_ID_PART_ID			GENMASK(27, 12)
13
14#define OCELOT_PART_ID			(0x7514 << 12)
15
16#define UART_UART			0x70100000
17
18static __init bool ocelot_detect(void)
19{
20	u32 rev;
21	int idx;
22
23	/* Look for the TLB entry set up by redboot before trying to use it */
24	write_c0_entryhi(DEVCPU_GCB_CHIP_REGS_CHIP_ID);
25	mtc0_tlbw_hazard();
26	tlb_probe();
27	tlb_probe_hazard();
28	idx = read_c0_index();
29	if (idx < 0)
30		return false;
31
32	/* A TLB entry exists, lets assume its usable and check the CHIP ID */
33	rev = __raw_readl((void __iomem *)DEVCPU_GCB_CHIP_REGS_CHIP_ID);
34
35	if ((rev & CHIP_ID_PART_ID) != OCELOT_PART_ID)
36		return false;
37
38	/* Copy command line from bootloader early for Initrd detection */
39	if (fw_arg0 < 10 && (fw_arg1 & 0xFFF00000) == 0x80000000) {
40		unsigned int prom_argc = fw_arg0;
41		const char **prom_argv = (const char **)fw_arg1;
42
43		if (prom_argc > 1 && strlen(prom_argv[1]) > 0)
44			/* ignore all built-in args if any f/w args given */
45			strscpy(arcs_cmdline, prom_argv[1]);
46	}
47
48	return true;
49}
50
51static void __init ocelot_earlyprintk_init(void)
52{
53	void __iomem *uart_base;
54
55	uart_base = ioremap(UART_UART, 0x20);
56	setup_8250_early_printk_port((unsigned long)uart_base, 2, 50000);
57}
58
59static void __init ocelot_late_init(void)
60{
61	ocelot_earlyprintk_init();
62}
63
64static __init const void *ocelot_fixup_fdt(const void *fdt,
65					   const void *match_data)
66{
67	/* This has to be done so late because ioremap needs to work */
68	late_time_init = ocelot_late_init;
69
70	return fdt;
71}
72
73extern char __dtb_ocelot_pcb123_begin[];
74
75MIPS_MACHINE(ocelot) = {
76	.fdt = __dtb_ocelot_pcb123_begin,
77	.fixup_fdt = ocelot_fixup_fdt,
78	.detect = ocelot_detect,
79};