linux-kernel - [PATCH V6 07/21] clk: tegra: Support for OSC context save and restore

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Message-ID: <1563738060-30213-8-git-send-email-skomatineni@nvidia.com>
Date:   Sun, 21 Jul 2019 12:40:46 -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>,
        <digetx@...il.com>, <devicetree@...r.kernel.org>
Subject: [PATCH V6 07/21] clk: tegra: Support for OSC context save and restore

X-NVConfidentiality: public

This patch adds support for saving OSC clock frequency and the
drive-strength during OSC clock init and creates an API to restore
OSC control register value from the saved context.

This API is invoked by Tegra210 clock driver during system resume
to restore the  OSC clock settings.

Acked-by: Thierry Reding <treding@...dia.com>
Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
---
 drivers/clk/tegra/clk-tegra-fixed.c | 15 +++++++++++++++
 drivers/clk/tegra/clk.h             |  1 +
 2 files changed, 16 insertions(+)

diff --git a/drivers/clk/tegra/clk-tegra-fixed.c b/drivers/clk/tegra/clk-tegra-fixed.c
index 8d91b2b191cf..7c6c8abfcde6 100644
--- a/drivers/clk/tegra/clk-tegra-fixed.c
+++ b/drivers/clk/tegra/clk-tegra-fixed.c
@@ -17,6 +17,10 @@
 #define OSC_CTRL			0x50
 #define OSC_CTRL_OSC_FREQ_SHIFT		28
 #define OSC_CTRL_PLL_REF_DIV_SHIFT	26
+#define OSC_CTRL_MASK			(0x3f2 |	\
+					(0xf << OSC_CTRL_OSC_FREQ_SHIFT))
+
+static u32 osc_ctrl_ctx;
 
 int __init tegra_osc_clk_init(void __iomem *clk_base, struct tegra_clk *clks,
 			      unsigned long *input_freqs, unsigned int num,
@@ -29,6 +33,7 @@ int __init tegra_osc_clk_init(void __iomem *clk_base, struct tegra_clk *clks,
 	unsigned osc_idx;
 
 	val = readl_relaxed(clk_base + OSC_CTRL);
+	osc_ctrl_ctx = val & OSC_CTRL_MASK;
 	osc_idx = val >> OSC_CTRL_OSC_FREQ_SHIFT;
 
 	if (osc_idx < num)
@@ -96,3 +101,13 @@ void __init tegra_fixed_clk_init(struct tegra_clk *tegra_clks)
 		*dt_clk = clk;
 	}
 }
+
+void tegra_clk_osc_resume(void __iomem *clk_base)
+{
+	u32 val;
+
+	val = readl_relaxed(clk_base + OSC_CTRL) & ~OSC_CTRL_MASK;
+	val |= osc_ctrl_ctx;
+	writel_relaxed(val, clk_base + OSC_CTRL);
+	fence_udelay(2, clk_base);
+}
diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
index 8532f5150091..3cd003b7512a 100644
--- a/drivers/clk/tegra/clk.h
+++ b/drivers/clk/tegra/clk.h
@@ -849,6 +849,7 @@ int tegra_pll_p_div_to_hw(struct tegra_clk_pll *pll, u8 p_div);
 int div_frac_get(unsigned long rate, unsigned parent_rate, u8 width,
 		 u8 frac_width, u8 flags);
 void tegra_clk_sync_state_pll(struct clk_hw *hw);
+void tegra_clk_osc_resume(void __iomem *clk_base);
 
 /* Combined read fence with delay */
 #define fence_udelay(delay, reg)	\
-- 
2.7.4