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Per SLIMbus specification, a reconfiguration sequence known as 'clock pause' needs to be broadcast over the bus while entering low- power mode. Clock-pause is initiated by the controller driver. To exit clock-pause, controller typically wakes up the framer device. Since wakeup precedure is controller-specific, framework calls it via controller's function pointer to invoke it. Signed-off-by: Sagar Dharia <sdharia@codeaurora.org> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> Reviwed-by: Mark Brown <broonie@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
122 lines
3.2 KiB
C
122 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2011-2017, The Linux Foundation
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*/
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#include <linux/errno.h>
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#include "slimbus.h"
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/**
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* slim_ctrl_clk_pause() - Called by slimbus controller to enter/exit
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* 'clock pause'
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* @ctrl: controller requesting bus to be paused or woken up
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* @wakeup: Wakeup this controller from clock pause.
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* @restart: Restart time value per spec used for clock pause. This value
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* isn't used when controller is to be woken up.
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*
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* Slimbus specification needs this sequence to turn-off clocks for the bus.
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* The sequence involves sending 3 broadcast messages (reconfiguration
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* sequence) to inform all devices on the bus.
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* To exit clock-pause, controller typically wakes up active framer device.
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* This API executes clock pause reconfiguration sequence if wakeup is false.
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* If wakeup is true, controller's wakeup is called.
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* For entering clock-pause, -EBUSY is returned if a message txn in pending.
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*/
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int slim_ctrl_clk_pause(struct slim_controller *ctrl, bool wakeup, u8 restart)
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{
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int i, ret = 0;
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unsigned long flags;
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struct slim_sched *sched = &ctrl->sched;
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struct slim_val_inf msg = {0, 0, NULL, NULL};
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DEFINE_SLIM_BCAST_TXN(txn, SLIM_MSG_MC_BEGIN_RECONFIGURATION,
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3, SLIM_LA_MANAGER, &msg);
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if (wakeup == false && restart > SLIM_CLK_UNSPECIFIED)
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return -EINVAL;
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mutex_lock(&sched->m_reconf);
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if (wakeup) {
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if (sched->clk_state == SLIM_CLK_ACTIVE) {
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mutex_unlock(&sched->m_reconf);
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return 0;
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}
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/*
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* Fine-tune calculation based on clock gear,
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* message-bandwidth after bandwidth management
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*/
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ret = wait_for_completion_timeout(&sched->pause_comp,
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msecs_to_jiffies(100));
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if (!ret) {
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mutex_unlock(&sched->m_reconf);
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pr_err("Previous clock pause did not finish");
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return -ETIMEDOUT;
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}
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ret = 0;
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/*
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* Slimbus framework will call controller wakeup
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* Controller should make sure that it sets active framer
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* out of clock pause
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*/
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if (sched->clk_state == SLIM_CLK_PAUSED && ctrl->wakeup)
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ret = ctrl->wakeup(ctrl);
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if (!ret)
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sched->clk_state = SLIM_CLK_ACTIVE;
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mutex_unlock(&sched->m_reconf);
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return ret;
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}
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/* already paused */
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if (ctrl->sched.clk_state == SLIM_CLK_PAUSED) {
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mutex_unlock(&sched->m_reconf);
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return 0;
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}
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spin_lock_irqsave(&ctrl->txn_lock, flags);
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for (i = 0; i < SLIM_MAX_TIDS; i++) {
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/* Pending response for a message */
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if (idr_find(&ctrl->tid_idr, i)) {
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spin_unlock_irqrestore(&ctrl->txn_lock, flags);
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mutex_unlock(&sched->m_reconf);
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return -EBUSY;
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}
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}
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spin_unlock_irqrestore(&ctrl->txn_lock, flags);
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sched->clk_state = SLIM_CLK_ENTERING_PAUSE;
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/* clock pause sequence */
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ret = slim_do_transfer(ctrl, &txn);
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if (ret)
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goto clk_pause_ret;
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txn.mc = SLIM_MSG_MC_NEXT_PAUSE_CLOCK;
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txn.rl = 4;
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msg.num_bytes = 1;
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msg.wbuf = &restart;
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ret = slim_do_transfer(ctrl, &txn);
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if (ret)
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goto clk_pause_ret;
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txn.mc = SLIM_MSG_MC_RECONFIGURE_NOW;
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txn.rl = 3;
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msg.num_bytes = 1;
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msg.wbuf = NULL;
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ret = slim_do_transfer(ctrl, &txn);
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clk_pause_ret:
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if (ret) {
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sched->clk_state = SLIM_CLK_ACTIVE;
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} else {
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sched->clk_state = SLIM_CLK_PAUSED;
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complete(&sched->pause_comp);
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}
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mutex_unlock(&sched->m_reconf);
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return ret;
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}
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EXPORT_SYMBOL_GPL(slim_ctrl_clk_pause);
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