1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright (c) 2011-2017, The Linux Foundation |
4 | */ |
5 | |
6 | #include <linux/errno.h> |
7 | #include "slimbus.h" |
8 | |
9 | /** |
10 | * slim_ctrl_clk_pause() - Called by slimbus controller to enter/exit |
11 | * 'clock pause' |
12 | * @ctrl: controller requesting bus to be paused or woken up |
13 | * @wakeup: Wakeup this controller from clock pause. |
14 | * @restart: Restart time value per spec used for clock pause. This value |
15 | * isn't used when controller is to be woken up. |
16 | * |
17 | * Slimbus specification needs this sequence to turn-off clocks for the bus. |
18 | * The sequence involves sending 3 broadcast messages (reconfiguration |
19 | * sequence) to inform all devices on the bus. |
20 | * To exit clock-pause, controller typically wakes up active framer device. |
21 | * This API executes clock pause reconfiguration sequence if wakeup is false. |
22 | * If wakeup is true, controller's wakeup is called. |
23 | * For entering clock-pause, -EBUSY is returned if a message txn in pending. |
24 | */ |
25 | int slim_ctrl_clk_pause(struct slim_controller *ctrl, bool wakeup, u8 restart) |
26 | { |
27 | int i, ret = 0; |
28 | unsigned long flags; |
29 | struct slim_sched *sched = &ctrl->sched; |
30 | struct slim_val_inf msg = {0, 0, NULL, NULL}; |
31 | |
32 | DEFINE_SLIM_BCAST_TXN(txn, SLIM_MSG_MC_BEGIN_RECONFIGURATION, |
33 | 3, SLIM_LA_MANAGER, &msg); |
34 | |
35 | if (wakeup == false && restart > SLIM_CLK_UNSPECIFIED) |
36 | return -EINVAL; |
37 | |
38 | mutex_lock(&sched->m_reconf); |
39 | if (wakeup) { |
40 | if (sched->clk_state == SLIM_CLK_ACTIVE) { |
41 | mutex_unlock(lock: &sched->m_reconf); |
42 | return 0; |
43 | } |
44 | |
45 | /* |
46 | * Fine-tune calculation based on clock gear, |
47 | * message-bandwidth after bandwidth management |
48 | */ |
49 | ret = wait_for_completion_timeout(x: &sched->pause_comp, |
50 | timeout: msecs_to_jiffies(m: 100)); |
51 | if (!ret) { |
52 | mutex_unlock(lock: &sched->m_reconf); |
53 | pr_err("Previous clock pause did not finish" ); |
54 | return -ETIMEDOUT; |
55 | } |
56 | ret = 0; |
57 | |
58 | /* |
59 | * Slimbus framework will call controller wakeup |
60 | * Controller should make sure that it sets active framer |
61 | * out of clock pause |
62 | */ |
63 | if (sched->clk_state == SLIM_CLK_PAUSED && ctrl->wakeup) |
64 | ret = ctrl->wakeup(ctrl); |
65 | if (!ret) |
66 | sched->clk_state = SLIM_CLK_ACTIVE; |
67 | mutex_unlock(lock: &sched->m_reconf); |
68 | |
69 | return ret; |
70 | } |
71 | |
72 | /* already paused */ |
73 | if (ctrl->sched.clk_state == SLIM_CLK_PAUSED) { |
74 | mutex_unlock(lock: &sched->m_reconf); |
75 | return 0; |
76 | } |
77 | |
78 | spin_lock_irqsave(&ctrl->txn_lock, flags); |
79 | for (i = 0; i < SLIM_MAX_TIDS; i++) { |
80 | /* Pending response for a message */ |
81 | if (idr_find(&ctrl->tid_idr, id: i)) { |
82 | spin_unlock_irqrestore(lock: &ctrl->txn_lock, flags); |
83 | mutex_unlock(lock: &sched->m_reconf); |
84 | return -EBUSY; |
85 | } |
86 | } |
87 | spin_unlock_irqrestore(lock: &ctrl->txn_lock, flags); |
88 | |
89 | sched->clk_state = SLIM_CLK_ENTERING_PAUSE; |
90 | |
91 | /* clock pause sequence */ |
92 | ret = slim_do_transfer(ctrl, txn: &txn); |
93 | if (ret) |
94 | goto clk_pause_ret; |
95 | |
96 | txn.mc = SLIM_MSG_MC_NEXT_PAUSE_CLOCK; |
97 | txn.rl = 4; |
98 | msg.num_bytes = 1; |
99 | msg.wbuf = &restart; |
100 | ret = slim_do_transfer(ctrl, txn: &txn); |
101 | if (ret) |
102 | goto clk_pause_ret; |
103 | |
104 | txn.mc = SLIM_MSG_MC_RECONFIGURE_NOW; |
105 | txn.rl = 3; |
106 | msg.num_bytes = 1; |
107 | msg.wbuf = NULL; |
108 | ret = slim_do_transfer(ctrl, txn: &txn); |
109 | |
110 | clk_pause_ret: |
111 | if (ret) { |
112 | sched->clk_state = SLIM_CLK_ACTIVE; |
113 | } else { |
114 | sched->clk_state = SLIM_CLK_PAUSED; |
115 | complete(&sched->pause_comp); |
116 | } |
117 | mutex_unlock(lock: &sched->m_reconf); |
118 | |
119 | return ret; |
120 | } |
121 | EXPORT_SYMBOL_GPL(slim_ctrl_clk_pause); |
122 | |