memory: tegra124-emc: Make driver modular

Add modularization support to the Tegra124 EMC driver, which now can be
compiled as a loadable kernel module.

Note that EMC clock must be registered at clk-init time, otherwise PLLM
will be disabled as unused clock at boot time if EMC driver is compiled
as a module. Hence add a prepare/complete callbacks. similarly to what is
done for the Tegra20/30 EMC drivers.

Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20201228154920.18846-2-digetx@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

1 files changed, 23 insertions, 3 deletions

diff --git a/drivers/clk/tegra/clk-tegra124.c b/drivers/clk/tegra/clk-tegra124.c
index e931319dcc9d..934520aab6e3 100644
--- a/drivers/clk/tegra/clk-tegra124.c
+++ b/drivers/clk/tegra/clk-tegra124.c
@@ -1500,6 +1500,26 @@ static void __init tegra124_132_clock_init_pre(struct device_node *np)
 	writel(plld_base, clk_base + PLLD_BASE);
 }
 
+static struct clk *tegra124_clk_src_onecell_get(struct of_phandle_args *clkspec,
+						void *data)
+{
+	struct clk_hw *hw;
+	struct clk *clk;
+
+	clk = of_clk_src_onecell_get(clkspec, data);
+	if (IS_ERR(clk))
+		return clk;
+
+	hw = __clk_get_hw(clk);
+
+	if (clkspec->args[0] == TEGRA124_CLK_EMC) {
+		if (!tegra124_clk_emc_driver_available(hw))
+			return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	return clk;
+}
+
 /**
  * tegra124_132_clock_init_post - clock initialization postamble for T124/T132
  * @np: struct device_node * of the DT node for the SoC CAR IP block
@@ -1516,10 +1536,10 @@ static void __init tegra124_132_clock_init_post(struct device_node *np)
 				  &pll_x_params);
 	tegra_init_special_resets(1, tegra124_reset_assert,
 				  tegra124_reset_deassert);
-	tegra_add_of_provider(np, of_clk_src_onecell_get);
+	tegra_add_of_provider(np, tegra124_clk_src_onecell_get);
 
-	clks[TEGRA124_CLK_EMC] = tegra_clk_register_emc(clk_base, np,
-							&emc_lock);
+	clks[TEGRA124_CLK_EMC] = tegra124_clk_register_emc(clk_base, np,
+							   &emc_lock);
 
 	tegra_register_devclks(devclks, ARRAY_SIZE(devclks));