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@gmail.com>
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

diff --git a/drivers/clk/tegra/clk-tegra20.c b/drivers/clk/tegra/clk-tegra20.c
index 68551effb5ca2f3956080953226289ea9886f78f..c71b61162a32f3706fcfb79c9eed4dd2e9f613d5 100644 (file)
--- a/drivers/clk/tegra/clk-tegra20.c
+++ b/drivers/clk/tegra/clk-tegra20.c
@@ -800,7 +800,9 @@ 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),
@@ -812,6 +814,14 @@ 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