linux-kernel - [PATCH v6 7/8] clk: tegra20: Check whether direct PLLM sourcing is turned off for EMC

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Message-Id: <20181021183052.32023-8-digetx@gmail.com>
Date:   Sun, 21 Oct 2018 21:30:51 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Prashant Gaikwad <pgaikwad@...dia.com>
Cc:     linux-tegra@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v6 7/8] clk: tegra20: Check whether direct PLLM sourcing is turned off for EMC

Ensure that direct PLLM sourcing is turned off for EMC as we don't support
that configuration in the clk driver.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
Acked-by: Peter De Schrijver <pdeschrijver@...dia.com>
Acked-by: Stephen Boyd <sboyd@...nel.org>
---
 drivers/clk/tegra/clk-tegra20.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/clk/tegra/clk-tegra20.c b/drivers/clk/tegra/clk-tegra20.c
index d3df56b6f2d1..f987ed361df6 100644
--- a/drivers/clk/tegra/clk-tegra20.c
+++ b/drivers/clk/tegra/clk-tegra20.c
@@ -806,7 +806,9 @@ static struct tegra_periph_init_data tegra_periph_nodiv_clk_list[] = {
 
 static void __init tegra20_emc_clk_init(void)
 {
+	const u32 use_pllm_ud = BIT(29);
 	struct clk *clk;
+	u32 emc_reg;
 
 	clk = clk_register_mux(NULL, "emc_mux", mux_pllmcp_clkm,
 			       ARRAY_SIZE(mux_pllmcp_clkm),
@@ -818,6 +820,14 @@ static void __init tegra20_emc_clk_init(void)
 				    &emc_lock);
 	clks[TEGRA20_CLK_MC] = clk;
 
+	/* un-divided pll_m_out0 is currently unsupported */
+	emc_reg = readl_relaxed(clk_base + CLK_SOURCE_EMC);
+	if (emc_reg & use_pllm_ud) {
+		pr_err("%s: un-divided PllM_out0 used as clock source\n",
+		       __func__);
+		return;
+	}
+
 	/*
 	 * Note that 'emc_mux' source and 'emc' rate shouldn't be changed at
 	 * the same time due to a HW bug, this won't happen because we're
-- 
2.19.0