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(&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(&sched->pause_comp, 50 msecs_to_jiffies(100)); 51 if (!ret) { 52 mutex_unlock(&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(&sched->m_reconf); 68 69 return ret; 70 } 71 72 /* already paused */ 73 if (ctrl->sched.clk_state == SLIM_CLK_PAUSED) { 74 mutex_unlock(&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, i)) { 82 spin_unlock_irqrestore(&ctrl->txn_lock, flags); 83 mutex_unlock(&sched->m_reconf); 84 return -EBUSY; 85 } 86 } 87 spin_unlock_irqrestore(&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); 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); 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); 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(&sched->m_reconf); 118 119 return ret; 120 } 121 EXPORT_SYMBOL_GPL(slim_ctrl_clk_pause); 122