linux-kernel - [PATCH V2 06/12] clk: tegra: add suspend resume support for DFLL clock

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Date:   Tue, 28 May 2019 16:08:50 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <tglx@...utronix.de>, <jason@...edaemon.net>,
        <marc.zyngier@....com>, <linus.walleij@...aro.org>,
        <stefan@...er.ch>, <mark.rutland@....com>
CC:     <pdeschrijver@...dia.com>, <pgaikwad@...dia.com>,
        <sboyd@...nel.org>, <linux-clk@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>, <jckuo@...dia.com>,
        <josephl@...dia.com>, <talho@...dia.com>, <skomatineni@...dia.com>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <mperttunen@...dia.com>, <spatra@...dia.com>, <robh+dt@...nel.org>,
        <devicetree@...r.kernel.org>
Subject: [PATCH V2 06/12] clk: tegra: add suspend resume support for DFLL clock

This patch adds support for suspend and resume for DFLL clock.

Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
---
 drivers/clk/tegra/clk-dfll.c | 82 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/clk/tegra/clk-dfll.h |  2 ++
 2 files changed, 84 insertions(+)

diff --git a/drivers/clk/tegra/clk-dfll.c b/drivers/clk/tegra/clk-dfll.c
index 1fc71baae13b..d92a5a05fbbc 100644
--- a/drivers/clk/tegra/clk-dfll.c
+++ b/drivers/clk/tegra/clk-dfll.c
@@ -286,6 +286,7 @@ struct tegra_dfll {
 	unsigned long			dvco_rate_min;
 
 	enum dfll_ctrl_mode		mode;
+	enum dfll_ctrl_mode		resume_mode;
 	enum dfll_tune_range		tune_range;
 	struct dentry			*debugfs_dir;
 	struct clk_hw			dfll_clk_hw;
@@ -1873,6 +1874,87 @@ static int dfll_fetch_common_params(struct tegra_dfll *td)
 }
 
 /*
+ * tegra_dfll_suspend
+ * @pdev: DFLL instance
+ *
+ * dfll controls clock/voltage to other devices, including CPU. Therefore,
+ * dfll driver pm suspend callback does not stop cl-dvfs operations. It is
+ * only used to enforce cold voltage limit, since SoC may cool down during
+ * suspend without waking up. The correct temperature zone after suspend will
+ * be updated via dfll cooling device interface during resume of temperature
+ * sensor.
+ */
+void tegra_dfll_suspend(struct platform_device *pdev)
+{
+	struct tegra_dfll *td = dev_get_drvdata(&pdev->dev);
+
+	if (!td)
+		return;
+
+	if (td->mode <= DFLL_DISABLED)
+		return;
+
+	td->resume_mode = td->mode;
+	switch (td->mode) {
+	case DFLL_CLOSED_LOOP:
+		dfll_set_mode(td, DFLL_CLOSED_LOOP);
+		dfll_set_frequency_request(td, &td->last_req);
+
+		dfll_unlock(td);
+		break;
+	default:
+		break;
+	}
+}
+
+/**
+ * tegra_dfll_resume - reprogram the DFLL after context-loss
+ * @pdev: DFLL instance
+ *
+ * Re-initialize and enable target device clock in open loop mode. Called
+ * directly from SoC clock resume syscore operation. Closed loop will be
+ * re-entered in platform syscore ops as well after CPU clock source is
+ * switched to DFLL in open loop.
+ */
+void tegra_dfll_resume(struct platform_device *pdev, bool on_dfll)
+{
+	struct tegra_dfll *td = dev_get_drvdata(&pdev->dev);
+
+	if (!td)
+		return;
+
+	if (on_dfll) {
+		if (td->resume_mode == DFLL_CLOSED_LOOP)
+			dfll_lock(td);
+		td->resume_mode = DFLL_DISABLED;
+		return;
+	}
+
+	reset_control_deassert(td->dvco_rst);
+
+	pm_runtime_get(td->dev);
+
+	/* Re-init DFLL */
+	dfll_init_out_if(td);
+	dfll_set_default_params(td);
+	dfll_set_open_loop_config(td);
+
+	pm_runtime_put(td->dev);
+
+	/* Restore last request and mode up to open loop */
+	switch (td->resume_mode) {
+	case DFLL_CLOSED_LOOP:
+	case DFLL_OPEN_LOOP:
+		dfll_set_mode(td, DFLL_OPEN_LOOP);
+		if (td->pmu_if == TEGRA_DFLL_PMU_I2C)
+			dfll_i2c_set_output_enabled(td, false);
+		break;
+	default:
+		break;
+	}
+}
+
+/*
  * API exported to per-SoC platform drivers
  */
 
diff --git a/drivers/clk/tegra/clk-dfll.h b/drivers/clk/tegra/clk-dfll.h
index 85d0d95223f3..44160b0495fe 100644
--- a/drivers/clk/tegra/clk-dfll.h
+++ b/drivers/clk/tegra/clk-dfll.h
@@ -48,6 +48,8 @@ struct tegra_dfll_soc_data {
 int tegra_dfll_register(struct platform_device *pdev,
 			struct tegra_dfll_soc_data *soc);
 struct tegra_dfll_soc_data *tegra_dfll_unregister(struct platform_device *pdev);
+void tegra_dfll_suspend(struct platform_device *pdev);
+void tegra_dfll_resume(struct platform_device *pdev, bool on_dfll);
 int tegra_dfll_runtime_suspend(struct device *dev);
 int tegra_dfll_runtime_resume(struct device *dev);
 
-- 
2.7.4