memory: tegra124-emc: Make driver modular

This patch adds modularization support to the Tegra124 EMC driver. Driver
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 this patch
adds prepare/complete callbacks, similar to what is done for Tegra20/30
EMC drivers.

Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>

drivers/clk/tegra/Makefile

@@ -22,7 +22,7 @@ obj-$(CONFIG_ARCH_TEGRA_3x_SOC)		+= clk-tegra20-emc.o
 obj-$(CONFIG_ARCH_TEGRA_114_SOC)	+= clk-tegra114.o
 obj-$(CONFIG_ARCH_TEGRA_124_SOC)	+= clk-tegra124.o
 obj-$(CONFIG_TEGRA_CLK_DFLL)		+= clk-tegra124-dfll-fcpu.o
-obj-$(CONFIG_TEGRA124_EMC)		+= clk-tegra124-emc.o
+obj-$(CONFIG_ARCH_TEGRA_124_SOC)	+= clk-tegra124-emc.o
 obj-$(CONFIG_ARCH_TEGRA_132_SOC)	+= clk-tegra124.o
 obj-y					+= cvb.o
 obj-$(CONFIG_ARCH_TEGRA_210_SOC)	+= clk-tegra210.o

drivers/clk/tegra/clk-tegra124-emc.c

@@ -11,7 +11,9 @@
 #include <linux/clk-provider.h>
 #include <linux/clk.h>
 #include <linux/clkdev.h>
+#include <linux/clk/tegra.h>
 #include <linux/delay.h>
+#include <linux/export.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
@@ -21,7 +23,6 @@
 #include <linux/string.h>
 
 #include <soc/tegra/fuse.h>
-#include <soc/tegra/emc.h>
 
 #include "clk.h"
 
@@ -80,6 +81,9 @@ struct tegra_clk_emc {
 	int num_timings;
 	struct emc_timing *timings;
 	spinlock_t *lock;
+
+	tegra124_emc_prepare_timing_change_cb *prepare_timing_change;
+	tegra124_emc_complete_timing_change_cb *complete_timing_change;
 };
 
 /* Common clock framework callback implementations */
@@ -176,6 +180,9 @@ static struct tegra_emc *emc_ensure_emc_driver(struct tegra_clk_emc *tegra)
 	if (tegra->emc)
 		return tegra->emc;
 
+	if (!tegra->prepare_timing_change || !tegra->complete_timing_change)
+		return NULL;
+
 	if (!tegra->emc_node)
 		return NULL;
 
@@ -241,7 +248,7 @@ static int emc_set_timing(struct tegra_clk_emc *tegra,
 
 	div = timing->parent_rate / (timing->rate / 2) - 2;
 
-	err = tegra_emc_prepare_timing_change(emc, timing->rate);
+	err = tegra->prepare_timing_change(emc, timing->rate);
 	if (err)
 		return err;
 
@@ -259,7 +266,7 @@ static int emc_set_timing(struct tegra_clk_emc *tegra,
 
 	spin_unlock_irqrestore(tegra->lock, flags);
 
-	tegra_emc_complete_timing_change(emc, timing->rate);
+	tegra->complete_timing_change(emc, timing->rate);
 
 	clk_hw_reparent(&tegra->hw, __clk_get_hw(timing->parent));
 	clk_disable_unprepare(tegra->prev_parent);
@@ -473,8 +480,8 @@ static const struct clk_ops tegra_clk_emc_ops = {
 	.get_parent = emc_get_parent,
 };
 
-struct clk *tegra_clk_register_emc(void __iomem *base, struct device_node *np,
-				   spinlock_t *lock)
+struct clk *tegra124_clk_register_emc(void __iomem *base, struct device_node *np,
+				      spinlock_t *lock)
 {
 	struct tegra_clk_emc *tegra;
 	struct clk_init_data init;
@@ -538,3 +545,27 @@ struct clk *tegra_clk_register_emc(void __iomem *base, struct device_node *np,
 
 	return clk;
 };
+
+void tegra124_clk_set_emc_callbacks(tegra124_emc_prepare_timing_change_cb *prep_cb,
+				    tegra124_emc_complete_timing_change_cb *complete_cb)
+{
+	struct clk *clk = __clk_lookup("emc");
+	struct tegra_clk_emc *tegra;
+	struct clk_hw *hw;
+
+	if (clk) {
+		hw = __clk_get_hw(clk);
+		tegra = container_of(hw, struct tegra_clk_emc, hw);
+
+		tegra->prepare_timing_change = prep_cb;
+		tegra->complete_timing_change = complete_cb;
+	}
+}
+EXPORT_SYMBOL_GPL(tegra124_clk_set_emc_callbacks);
+
+bool tegra124_clk_emc_driver_available(struct clk_hw *hw)
+{
+	struct tegra_clk_emc *tegra = container_of(hw, struct tegra_clk_emc, hw);
+
+	return tegra->prepare_timing_change && tegra->complete_timing_change;
+}

drivers/clk/tegra/clk-tegra124.c

@@ -929,6 +929,7 @@ static struct tegra_clk tegra124_clks[tegra_clk_max] __initdata = {
 	[tegra_clk_audio4_mux] = { .dt_id = TEGRA124_CLK_AUDIO4_MUX, .present = true },
 	[tegra_clk_spdif_mux] = { .dt_id = TEGRA124_CLK_SPDIF_MUX, .present = true },
 	[tegra_clk_cec] = { .dt_id = TEGRA124_CLK_CEC, .present = true },
+	[tegra_clk_emc] = { .dt_id = TEGRA124_CLK_EMC, .present = false },
 };
 
 static struct tegra_devclk devclks[] __initdata = {
@@ -1500,6 +1501,26 @@ 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 +1537,10 @@ 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));
 

drivers/clk/tegra/clk.h

@@ -881,18 +881,6 @@ void tegra_super_clk_gen5_init(void __iomem *clk_base,
 			void __iomem *pmc_base, struct tegra_clk *tegra_clks,
 			struct tegra_clk_pll_params *pll_params);
 
-#ifdef CONFIG_TEGRA124_EMC
-struct clk *tegra_clk_register_emc(void __iomem *base, struct device_node *np,
-				   spinlock_t *lock);
-#else
-static inline struct clk *tegra_clk_register_emc(void __iomem *base,
-						 struct device_node *np,
-						 spinlock_t *lock)
-{
-	return NULL;
-}
-#endif
-
 void tegra114_clock_tune_cpu_trimmers_high(void);
 void tegra114_clock_tune_cpu_trimmers_low(void);
 void tegra114_clock_tune_cpu_trimmers_init(void);
@@ -922,6 +910,10 @@ void tegra_clk_periph_resume(void);
 bool tegra20_clk_emc_driver_available(struct clk_hw *emc_hw);
 struct clk *tegra20_clk_register_emc(void __iomem *ioaddr, bool low_jitter);
 
+struct clk *tegra124_clk_register_emc(void __iomem *base, struct device_node *np,
+				      spinlock_t *lock);
+bool tegra124_clk_emc_driver_available(struct clk_hw *emc_hw);
+
 struct clk *tegra210_clk_register_emc(struct device_node *np,
 				      void __iomem *regs);
 

drivers/memory/tegra/Kconfig

@@ -31,7 +31,7 @@ config TEGRA30_EMC
 	  external memory.
 
 config TEGRA124_EMC
-	bool "NVIDIA Tegra124 External Memory Controller driver"
+	tristate "NVIDIA Tegra124 External Memory Controller driver"
 	default y
 	depends on TEGRA_MC && ARCH_TEGRA_124_SOC
 	help

drivers/memory/tegra/tegra124-emc.c

@@ -9,16 +9,17 @@
 #include <linux/clk-provider.h>
 #include <linux/clk.h>
 #include <linux/clkdev.h>
+#include <linux/clk/tegra.h>
 #include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/io.h>
+#include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/sort.h>
 #include <linux/string.h>
 
-#include <soc/tegra/emc.h>
 #include <soc/tegra/fuse.h>
 #include <soc/tegra/mc.h>
 
@@ -562,8 +563,8 @@ static struct emc_timing *tegra_emc_find_timing(struct tegra_emc *emc,
 	return timing;
 }
 
-int tegra_emc_prepare_timing_change(struct tegra_emc *emc,
-				    unsigned long rate)
+static int tegra_emc_prepare_timing_change(struct tegra_emc *emc,
+					   unsigned long rate)
 {
 	struct emc_timing *timing = tegra_emc_find_timing(emc, rate);
 	struct emc_timing *last = &emc->last_timing;
@@ -790,8 +791,8 @@ int tegra_emc_prepare_timing_change(struct tegra_emc *emc,
 	return 0;
 }
 
-void tegra_emc_complete_timing_change(struct tegra_emc *emc,
-				      unsigned long rate)
+static void tegra_emc_complete_timing_change(struct tegra_emc *emc,
+					     unsigned long rate)
 {
 	struct emc_timing *timing = tegra_emc_find_timing(emc, rate);
 	struct emc_timing *last = &emc->last_timing;
@@ -987,6 +988,7 @@ static const struct of_device_id tegra_emc_of_match[] = {
 	{ .compatible = "nvidia,tegra132-emc" },
 	{}
 };
+MODULE_DEVICE_TABLE(of, tegra_emc_of_match);
 
 static struct device_node *
 tegra_emc_find_node_by_ram_code(struct device_node *node, u32 ram_code)
@@ -1228,9 +1230,19 @@ static int tegra_emc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, emc);
 
+	tegra124_clk_set_emc_callbacks(tegra_emc_prepare_timing_change,
+				       tegra_emc_complete_timing_change);
+
 	if (IS_ENABLED(CONFIG_DEBUG_FS))
 		emc_debugfs_init(&pdev->dev, emc);
 
+	/*
+	 * Don't allow the kernel module to be unloaded. Unloading adds some
+	 * extra complexity which doesn't really worth the effort in a case of
+	 * this driver.
+	 */
+	try_module_get(THIS_MODULE);
+
 	return 0;
 };
 
@@ -1242,9 +1254,8 @@ static struct platform_driver tegra_emc_driver = {
 		.suppress_bind_attrs = true,
 	},
 };
+module_platform_driver(tegra_emc_driver);
 
-static int tegra_emc_init(void)
-{
-	return platform_driver_register(&tegra_emc_driver);
-}
-subsys_initcall(tegra_emc_init);
+MODULE_AUTHOR("Mikko Perttunen <mperttunen@nvidia.com>");
+MODULE_DESCRIPTION("NVIDIA Tegra124 EMC driver");
+MODULE_LICENSE("GPL v2");

include/linux/clk/tegra.h

@@ -136,6 +136,8 @@ extern void tegra210_clk_emc_dll_update_setting(u32 emc_dll_src_value);
 extern void tegra210_clk_emc_update_setting(u32 emc_src_value);
 
 struct clk;
+struct device_node;
+struct tegra_emc;
 
 typedef long (tegra20_clk_emc_round_cb)(unsigned long rate,
 					unsigned long min_rate,
@@ -146,6 +148,13 @@ void tegra20_clk_set_emc_round_callback(tegra20_clk_emc_round_cb *round_cb,
 					void *cb_arg);
 int tegra20_clk_prepare_emc_mc_same_freq(struct clk *emc_clk, bool same);
 
+typedef int (tegra124_emc_prepare_timing_change_cb)(struct tegra_emc *emc,
+						    unsigned long rate);
+typedef void (tegra124_emc_complete_timing_change_cb)(struct tegra_emc *emc,
+						      unsigned long rate);
+void tegra124_clk_set_emc_callbacks(tegra124_emc_prepare_timing_change_cb *prep_cb,
+				    tegra124_emc_complete_timing_change_cb *complete_cb);
+
 struct tegra210_clk_emc_config {
 	unsigned long rate;
 	bool same_freq;