xref: /openbmc/linux/drivers/thunderbolt/nhi_ops.c (revision 61163895)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * NHI specific operations
4  *
5  * Copyright (C) 2019, Intel Corporation
6  * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
7  */
8 
9 #include <linux/delay.h>
10 #include <linux/suspend.h>
11 
12 #include "nhi.h"
13 #include "nhi_regs.h"
14 #include "tb.h"
15 
16 /* Ice Lake specific NHI operations */
17 
18 #define ICL_LC_MAILBOX_TIMEOUT	500 /* ms */
19 
20 static int check_for_device(struct device *dev, void *data)
21 {
22 	return tb_is_switch(dev);
23 }
24 
25 static bool icl_nhi_is_device_connected(struct tb_nhi *nhi)
26 {
27 	struct tb *tb = pci_get_drvdata(nhi->pdev);
28 	int ret;
29 
30 	ret = device_for_each_child(&tb->root_switch->dev, NULL,
31 				    check_for_device);
32 	return ret > 0;
33 }
34 
35 static int icl_nhi_force_power(struct tb_nhi *nhi, bool power)
36 {
37 	u32 vs_cap;
38 
39 	/*
40 	 * The Thunderbolt host controller is present always in Ice Lake
41 	 * but the firmware may not be loaded and running (depending
42 	 * whether there is device connected and so on). Each time the
43 	 * controller is used we need to "Force Power" it first and wait
44 	 * for the firmware to indicate it is up and running. This "Force
45 	 * Power" is really not about actually powering on/off the
46 	 * controller so it is accessible even if "Force Power" is off.
47 	 *
48 	 * The actual power management happens inside shared ACPI power
49 	 * resources using standard ACPI methods.
50 	 */
51 	pci_read_config_dword(nhi->pdev, VS_CAP_22, &vs_cap);
52 	if (power) {
53 		vs_cap &= ~VS_CAP_22_DMA_DELAY_MASK;
54 		vs_cap |= 0x22 << VS_CAP_22_DMA_DELAY_SHIFT;
55 		vs_cap |= VS_CAP_22_FORCE_POWER;
56 	} else {
57 		vs_cap &= ~VS_CAP_22_FORCE_POWER;
58 	}
59 	pci_write_config_dword(nhi->pdev, VS_CAP_22, vs_cap);
60 
61 	if (power) {
62 		unsigned int retries = 10;
63 		u32 val;
64 
65 		/* Wait until the firmware tells it is up and running */
66 		do {
67 			pci_read_config_dword(nhi->pdev, VS_CAP_9, &val);
68 			if (val & VS_CAP_9_FW_READY)
69 				return 0;
70 			msleep(250);
71 		} while (--retries);
72 
73 		return -ETIMEDOUT;
74 	}
75 
76 	return 0;
77 }
78 
79 static void icl_nhi_lc_mailbox_cmd(struct tb_nhi *nhi, enum icl_lc_mailbox_cmd cmd)
80 {
81 	u32 data;
82 
83 	data = (cmd << VS_CAP_19_CMD_SHIFT) & VS_CAP_19_CMD_MASK;
84 	pci_write_config_dword(nhi->pdev, VS_CAP_19, data | VS_CAP_19_VALID);
85 }
86 
87 static int icl_nhi_lc_mailbox_cmd_complete(struct tb_nhi *nhi, int timeout)
88 {
89 	unsigned long end;
90 	u32 data;
91 
92 	if (!timeout)
93 		goto clear;
94 
95 	end = jiffies + msecs_to_jiffies(timeout);
96 	do {
97 		pci_read_config_dword(nhi->pdev, VS_CAP_18, &data);
98 		if (data & VS_CAP_18_DONE)
99 			goto clear;
100 		msleep(100);
101 	} while (time_before(jiffies, end));
102 
103 	return -ETIMEDOUT;
104 
105 clear:
106 	/* Clear the valid bit */
107 	pci_write_config_dword(nhi->pdev, VS_CAP_19, 0);
108 	return 0;
109 }
110 
111 static void icl_nhi_set_ltr(struct tb_nhi *nhi)
112 {
113 	u32 max_ltr, ltr;
114 
115 	pci_read_config_dword(nhi->pdev, VS_CAP_16, &max_ltr);
116 	max_ltr &= 0xffff;
117 	/* Program the same value for both snoop and no-snoop */
118 	ltr = max_ltr << 16 | max_ltr;
119 	pci_write_config_dword(nhi->pdev, VS_CAP_15, ltr);
120 }
121 
122 static int icl_nhi_suspend(struct tb_nhi *nhi)
123 {
124 	int ret;
125 
126 	if (icl_nhi_is_device_connected(nhi))
127 		return 0;
128 
129 	/*
130 	 * If there is no device connected we need to perform both: a
131 	 * handshake through LC mailbox and force power down before
132 	 * entering D3.
133 	 */
134 	icl_nhi_lc_mailbox_cmd(nhi, ICL_LC_PREPARE_FOR_RESET);
135 	ret = icl_nhi_lc_mailbox_cmd_complete(nhi, ICL_LC_MAILBOX_TIMEOUT);
136 	if (ret)
137 		return ret;
138 
139 	return icl_nhi_force_power(nhi, false);
140 }
141 
142 static int icl_nhi_suspend_noirq(struct tb_nhi *nhi, bool wakeup)
143 {
144 	enum icl_lc_mailbox_cmd cmd;
145 
146 	if (!pm_suspend_via_firmware())
147 		return icl_nhi_suspend(nhi);
148 
149 	cmd = wakeup ? ICL_LC_GO2SX : ICL_LC_GO2SX_NO_WAKE;
150 	icl_nhi_lc_mailbox_cmd(nhi, cmd);
151 	return icl_nhi_lc_mailbox_cmd_complete(nhi, ICL_LC_MAILBOX_TIMEOUT);
152 }
153 
154 static int icl_nhi_resume(struct tb_nhi *nhi)
155 {
156 	int ret;
157 
158 	ret = icl_nhi_force_power(nhi, true);
159 	if (ret)
160 		return ret;
161 
162 	icl_nhi_set_ltr(nhi);
163 	return 0;
164 }
165 
166 static void icl_nhi_shutdown(struct tb_nhi *nhi)
167 {
168 	icl_nhi_force_power(nhi, false);
169 }
170 
171 const struct tb_nhi_ops icl_nhi_ops = {
172 	.init = icl_nhi_resume,
173 	.suspend_noirq = icl_nhi_suspend_noirq,
174 	.resume_noirq = icl_nhi_resume,
175 	.runtime_suspend = icl_nhi_suspend,
176 	.runtime_resume = icl_nhi_resume,
177 	.shutdown = icl_nhi_shutdown,
178 };
179