linux-kernel - [PATCH v7 6/8] clk: tegra: cclk: Handle thermal DIV2 CPU frequency throttling

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Date:   Tue, 11 May 2021 02:17:35 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Prashant Gaikwad <pgaikwad@...dia.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>
Cc:     linux-tegra@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: [PATCH v7 6/8] clk: tegra: cclk: Handle thermal DIV2 CPU frequency throttling

Check whether thermal DIV2 throttle is active in order to report
the CPU frequency properly. This very useful for userspace tools
like cpufreq-info which show actual frequency asserted from hardware.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/clk/tegra/clk-tegra-super-cclk.c | 16 ++++++++++++++--
 drivers/clk/tegra/clk-tegra30.c          |  2 +-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/tegra/clk-tegra-super-cclk.c b/drivers/clk/tegra/clk-tegra-super-cclk.c
index a03119c30456..f75822b71d0e 100644
--- a/drivers/clk/tegra/clk-tegra-super-cclk.c
+++ b/drivers/clk/tegra/clk-tegra-super-cclk.c
@@ -25,6 +25,8 @@
 
 #define SUPER_CDIV_ENB		BIT(31)
 
+#define TSENSOR_SLOWDOWN	BIT(23)
+
 static struct tegra_clk_super_mux *cclk_super;
 static bool cclk_on_pllx;
 
@@ -47,10 +49,20 @@ static int cclk_super_set_rate(struct clk_hw *hw, unsigned long rate,
 static unsigned long cclk_super_recalc_rate(struct clk_hw *hw,
 					    unsigned long parent_rate)
 {
+	struct tegra_clk_super_mux *super = to_clk_super_mux(hw);
+	u32 val = readl_relaxed(super->reg);
+	unsigned int div2;
+
+	/* check whether thermal throttling is active */
+	if (val & TSENSOR_SLOWDOWN)
+		div2 = 2;
+	else
+		div2 = 1;
+
 	if (cclk_super_get_parent(hw) == PLLX_INDEX)
-		return parent_rate;
+		return parent_rate / div2;
 
-	return tegra_clk_super_ops.recalc_rate(hw, parent_rate);
+	return tegra_clk_super_ops.recalc_rate(hw, parent_rate) / div2;
 }
 
 static int cclk_super_determine_rate(struct clk_hw *hw,
diff --git a/drivers/clk/tegra/clk-tegra30.c b/drivers/clk/tegra/clk-tegra30.c
index a33688b2359e..5b6bd138be84 100644
--- a/drivers/clk/tegra/clk-tegra30.c
+++ b/drivers/clk/tegra/clk-tegra30.c
@@ -930,7 +930,7 @@ static void __init tegra30_super_clk_init(void)
 	/* CCLKG */
 	clk = tegra_clk_register_super_cclk("cclk_g", cclk_g_parents,
 				  ARRAY_SIZE(cclk_g_parents),
-				  CLK_SET_RATE_PARENT,
+				  CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE,
 				  clk_base + CCLKG_BURST_POLICY,
 				  0, NULL);
 	clks[TEGRA30_CLK_CCLK_G] = clk;
-- 
2.30.2