1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Device Tree support for MStar/Sigmastar Armv7 SoCs
4 *
5 * Copyright (c) 2020 thingy.jp
6 * Author: Daniel Palmer <daniel@thingy.jp>
7 */
8
9 #include <linux/init.h>
10 #include <asm/mach/arch.h>
11 #include <asm/mach/map.h>
12 #include <linux/of.h>
13 #include <linux/of_address.h>
14 #include <linux/io.h>
15
16 /*
17 * In the u-boot code the area these registers are in is
18 * called "L3 bridge" and there are register descriptions
19 * for something in the same area called "AXI".
20 *
21 * It's not exactly known what this is but the vendor code
22 * for both u-boot and linux share calls to "flush the miu pipe".
23 * This seems to be to force pending CPU writes to memory so that
24 * the state is right before DMA capable devices try to read
25 * descriptors and data the CPU has prepared. Without doing this
26 * ethernet doesn't work reliably for example.
27 */
28
29 #define MSTARV7_L3BRIDGE_FLUSH 0x14
30 #define MSTARV7_L3BRIDGE_STATUS 0x40
31 #define MSTARV7_L3BRIDGE_FLUSH_TRIGGER BIT(0)
32 #define MSTARV7_L3BRIDGE_STATUS_DONE BIT(12)
33
34 #ifdef CONFIG_SMP
35 #define MSTARV7_CPU1_BOOT_ADDR_HIGH 0x4c
36 #define MSTARV7_CPU1_BOOT_ADDR_LOW 0x50
37 #define MSTARV7_CPU1_UNLOCK 0x58
38 #define MSTARV7_CPU1_UNLOCK_MAGIC 0xbabe
39 #endif
40
41 static void __iomem *l3bridge;
42
43 static const char * const mstarv7_board_dt_compat[] __initconst = {
44 "mstar,infinity",
45 "mstar,infinity2m",
46 "mstar,infinity3",
47 "mstar,mercury5",
48 NULL,
49 };
50
51 /*
52 * This may need locking to deal with situations where an interrupt
53 * happens while we are in here and mb() gets called by the interrupt handler.
54 *
55 * The vendor code did have a spin lock but it doesn't seem to be needed and
56 * removing it hasn't caused any side effects so far.
57 *
58 * [writel|readl]_relaxed have to be used here because otherwise
59 * we'd end up right back in here.
60 */
61 static void mstarv7_mb(void)
62 {
63 /* toggle the flush miu pipe fire bit */
64 writel_relaxed(0, l3bridge + MSTARV7_L3BRIDGE_FLUSH);
65 writel_relaxed(MSTARV7_L3BRIDGE_FLUSH_TRIGGER, l3bridge
66 + MSTARV7_L3BRIDGE_FLUSH);
67 while (!(readl_relaxed(l3bridge + MSTARV7_L3BRIDGE_STATUS)
68 & MSTARV7_L3BRIDGE_STATUS_DONE)) {
69 /* wait for flush to complete */
70 }
71 }
72
73 #ifdef CONFIG_SMP
74 static int mstarv7_boot_secondary(unsigned int cpu, struct task_struct *idle)
75 {
76 struct device_node *np;
77 u32 bootaddr = (u32) __pa_symbol(secondary_startup_arm);
78 void __iomem *smpctrl;
79
80 /*
81 * right now we don't know how to boot anything except
82 * cpu 1.
83 */
84 if (cpu != 1)
85 return -EINVAL;
86
87 np = of_find_compatible_node(NULL, NULL, "mstar,smpctrl");
88 smpctrl = of_iomap(np, 0);
89
90 if (!smpctrl)
91 return -ENODEV;
92
93 /* set the boot address for the second cpu */
94 writew(bootaddr & 0xffff, smpctrl + MSTARV7_CPU1_BOOT_ADDR_LOW);
95 writew((bootaddr >> 16) & 0xffff, smpctrl + MSTARV7_CPU1_BOOT_ADDR_HIGH);
96
97 /* unlock the second cpu */
98 writew(MSTARV7_CPU1_UNLOCK_MAGIC, smpctrl + MSTARV7_CPU1_UNLOCK);
99
100 /* and away we go...*/
101 arch_send_wakeup_ipi_mask(cpumask_of(cpu));
102
103 iounmap(smpctrl);
104
105 return 0;
106 }
107
108 static const struct smp_operations __initdata mstarv7_smp_ops = {
109 .smp_boot_secondary = mstarv7_boot_secondary,
110 };
111 #endif
112
113 static void __init mstarv7_init(void)
114 {
115 struct device_node *np;
116
117 np = of_find_compatible_node(NULL, NULL, "mstar,l3bridge");
118 l3bridge = of_iomap(np, 0);
119 if (l3bridge)
120 soc_mb = mstarv7_mb;
121 else
122 pr_warn("Failed to install memory barrier, DMA will be broken!\n");
123 }
124
125 DT_MACHINE_START(MSTARV7_DT, "MStar/Sigmastar Armv7 (Device Tree)")
126 .dt_compat = mstarv7_board_dt_compat,
127 .init_machine = mstarv7_init,
128 .smp = smp_ops(mstarv7_smp_ops),
129 MACHINE_END
130
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