clk: tegra: Implement memory-controller clock

The memory controller clock runs either at half or the same frequency as
the EMC clock.

Reviewed-By: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/clk/tegra/clk-tegra124.c b/drivers/clk/tegra/clk-tegra124.c
index e3a8584..f5f9bac 100644
--- a/drivers/clk/tegra/clk-tegra124.c
+++ b/drivers/clk/tegra/clk-tegra124.c
@@ -132,6 +132,7 @@
 static DEFINE_SPINLOCK(pll_e_lock);
 static DEFINE_SPINLOCK(pll_re_lock);
 static DEFINE_SPINLOCK(pll_u_lock);
+static DEFINE_SPINLOCK(emc_lock);
 
 /* possible OSC frequencies in Hz */
 static unsigned long tegra124_input_freq[] = {
@@ -1127,7 +1128,11 @@
 	clk = clk_register_mux(NULL, "emc_mux", mux_pllmcp_clkm,
 			       ARRAY_SIZE(mux_pllmcp_clkm), 0,
 			       clk_base + CLK_SOURCE_EMC,
-			       29, 3, 0, NULL);
+			       29, 3, 0, &emc_lock);
+
+	clk = tegra_clk_register_mc("mc", "emc_mux", clk_base + CLK_SOURCE_EMC,
+				    &emc_lock);
+	clks[TEGRA124_CLK_MC] = clk;
 
 	/* cml0 */
 	clk = clk_register_gate(NULL, "cml0", "pll_e", 0, clk_base + PLLE_AUX,