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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, &regs->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(&regs->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++, &regs->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(&regs->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