1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (c) 2017 Intel Corporation
4 *
5 * Intel Mobile Internet Devices (MID) based on Intel Atom SoCs have few
6 * microcontrollers inside to do some auxiliary tasks. One of such
7 * microcontroller is System Controller Unit (SCU) which, in particular,
8 * is servicing watchdog and controlling system reset function.
9 *
10 * This driver enables IPC channel to SCU.
11 */
12 #include <common.h>
13 #include <dm.h>
14 #include <regmap.h>
15 #include <syscon.h>
16 #include <asm/cpu.h>
17 #include <asm/scu.h>
18 #include <linux/errno.h>
19 #include <linux/io.h>
20 #include <linux/kernel.h>
21
22 /* SCU register map */
23 struct ipc_regs {
24 u32 cmd;
25 u32 status;
26 u32 sptr;
27 u32 dptr;
28 u32 reserved[28];
29 u32 wbuf[4];
30 u32 rbuf[4];
31 };
32
33 struct scu {
34 struct ipc_regs *regs;
35 };
36
37 /**
38 * scu_ipc_send_command() - send command to SCU
39 * @regs: register map of SCU
40 * @cmd: command
41 *
42 * Command Register (Write Only):
43 * A write to this register results in an interrupt to the SCU core processor
44 * Format:
45 * |rfu2(8) | size(8) | command id(4) | rfu1(3) | ioc(1) | command(8)|
46 */
scu_ipc_send_command(struct ipc_regs * regs,u32 cmd)47 static void scu_ipc_send_command(struct ipc_regs *regs, u32 cmd)
48 {
49 writel(cmd, ®s->cmd);
50 }
51
52 /**
53 * scu_ipc_check_status() - check status of last command
54 * @regs: register map of SCU
55 *
56 * Status Register (Read Only):
57 * Driver will read this register to get the ready/busy status of the IPC
58 * block and error status of the IPC command that was just processed by SCU
59 * Format:
60 * |rfu3(8)|error code(8)|initiator id(8)|cmd id(4)|rfu1(2)|error(1)|busy(1)|
61 */
scu_ipc_check_status(struct ipc_regs * regs)62 static int scu_ipc_check_status(struct ipc_regs *regs)
63 {
64 int loop_count = 100000;
65 int status;
66
67 do {
68 status = readl(®s->status);
69 if (!(status & BIT(0)))
70 break;
71
72 udelay(1);
73 } while (--loop_count);
74 if (!loop_count)
75 return -ETIMEDOUT;
76
77 if (status & BIT(1)) {
78 printf("%s() status=0x%08x\n", __func__, status);
79 return -EIO;
80 }
81
82 return 0;
83 }
84
scu_ipc_cmd(struct ipc_regs * regs,u32 cmd,u32 sub,u32 * in,int inlen,u32 * out,int outlen)85 static int scu_ipc_cmd(struct ipc_regs *regs, u32 cmd, u32 sub,
86 u32 *in, int inlen, u32 *out, int outlen)
87 {
88 int i, err;
89
90 for (i = 0; i < inlen; i++)
91 writel(*in++, ®s->wbuf[i]);
92
93 scu_ipc_send_command(regs, (inlen << 16) | (sub << 12) | cmd);
94 err = scu_ipc_check_status(regs);
95
96 if (!err) {
97 for (i = 0; i < outlen; i++)
98 *out++ = readl(®s->rbuf[i]);
99 }
100
101 return err;
102 }
103
104 /**
105 * scu_ipc_simple_command() - send a simple command
106 * @cmd: command
107 * @sub: sub type
108 *
109 * Issue a simple command to the SCU. Do not use this interface if
110 * you must then access data as any data values may be overwritten
111 * by another SCU access by the time this function returns.
112 *
113 * This function may sleep. Locking for SCU accesses is handled for
114 * the caller.
115 */
scu_ipc_simple_command(u32 cmd,u32 sub)116 int scu_ipc_simple_command(u32 cmd, u32 sub)
117 {
118 struct scu *scu;
119 struct udevice *dev;
120 int ret;
121
122 ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev);
123 if (ret)
124 return ret;
125
126 scu = dev_get_priv(dev);
127
128 scu_ipc_send_command(scu->regs, sub << 12 | cmd);
129 return scu_ipc_check_status(scu->regs);
130 }
131
scu_ipc_command(u32 cmd,u32 sub,u32 * in,int inlen,u32 * out,int outlen)132 int scu_ipc_command(u32 cmd, u32 sub, u32 *in, int inlen, u32 *out, int outlen)
133 {
134 struct scu *scu;
135 struct udevice *dev;
136 int ret;
137
138 ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev);
139 if (ret)
140 return ret;
141
142 scu = dev_get_priv(dev);
143
144 return scu_ipc_cmd(scu->regs, cmd, sub, in, inlen, out, outlen);
145 }
146
scu_ipc_probe(struct udevice * dev)147 static int scu_ipc_probe(struct udevice *dev)
148 {
149 struct scu *scu = dev_get_priv(dev);
150
151 scu->regs = syscon_get_first_range(X86_SYSCON_SCU);
152
153 return 0;
154 }
155
156 static const struct udevice_id scu_ipc_match[] = {
157 { .compatible = "intel,scu-ipc", .data = X86_SYSCON_SCU },
158 { /* sentinel */ }
159 };
160
161 U_BOOT_DRIVER(scu_ipc) = {
162 .name = "scu_ipc",
163 .id = UCLASS_SYSCON,
164 .of_match = scu_ipc_match,
165 .probe = scu_ipc_probe,
166 .priv_auto_alloc_size = sizeof(struct scu),
167 };
168