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 <kwiz...@gmail.com>
Signed-off-by: Dmitry Osipenko <dig...@gmail.com>
---
 drivers/clk/tegra/Kconfig            |  3 ++
 drivers/clk/tegra/Makefile           |  2 +-
 drivers/clk/tegra/clk-tegra124-emc.c | 41 ++++++++++++++++++++++++----
 drivers/clk/tegra/clk-tegra124.c     | 26 ++++++++++++++++--
 drivers/clk/tegra/clk.h              | 18 ++++++++----
 drivers/memory/tegra/Kconfig         |  3 +-
 drivers/memory/tegra/tegra124-emc.c  | 31 ++++++++++++++-------
 include/linux/clk/tegra.h            |  8 ++++++
 include/soc/tegra/emc.h              | 16 -----------
 9 files changed, 106 insertions(+), 42 deletions(-)
 delete mode 100644 include/soc/tegra/emc.h

diff --git a/drivers/clk/tegra/Kconfig b/drivers/clk/tegra/Kconfig
index deaa4605824c..90df619dc087 100644
--- a/drivers/clk/tegra/Kconfig
+++ b/drivers/clk/tegra/Kconfig
@@ -7,3 +7,6 @@ config TEGRA_CLK_DFLL
        depends on ARCH_TEGRA_124_SOC || ARCH_TEGRA_210_SOC
        select PM_OPP
        def_bool y
+
+config TEGRA124_CLK_EMC
+       bool
diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
index eec2313fd37e..7b1816856eb5 100644
--- a/drivers/clk/tegra/Makefile
+++ b/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_TEGRA124_CLK_EMC)         += 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
diff --git a/drivers/clk/tegra/clk-tegra124-emc.c 
b/drivers/clk/tegra/clk-tegra124-emc.c
index 745f9faa98d8..bdf6f4a51617 100644
--- a/drivers/clk/tegra/clk-tegra124-emc.c
+++ b/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;
+}
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));
 
diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
index 6b565f6b5f66..c3e36b5dcc75 100644
--- a/drivers/clk/tegra/clk.h
+++ b/drivers/clk/tegra/clk.h
@@ -881,16 +881,22 @@ 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);
+#ifdef CONFIG_TEGRA124_CLK_EMC
+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);
 #else
-static inline struct clk *tegra_clk_register_emc(void __iomem *base,
-                                                struct device_node *np,
-                                                spinlock_t *lock)
+static inline struct clk *
+tegra124_clk_register_emc(void __iomem *base, struct device_node *np,
+                         spinlock_t *lock)
 {
        return NULL;
 }
+
+static inline bool tegra124_clk_emc_driver_available(struct clk_hw *emc_hw)
+{
+       return false;
+}
 #endif
 
 void tegra114_clock_tune_cpu_trimmers_high(void);
diff --git a/drivers/memory/tegra/Kconfig b/drivers/memory/tegra/Kconfig
index ca7077a06f4c..f5b451403c58 100644
--- a/drivers/memory/tegra/Kconfig
+++ b/drivers/memory/tegra/Kconfig
@@ -32,9 +32,10 @@ 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
+       select TEGRA124_CLK_EMC
        help
          This driver is for the External Memory Controller (EMC) found on
          Tegra124 chips. The EMC controls the external DRAM on the board.
diff --git a/drivers/memory/tegra/tegra124-emc.c 
b/drivers/memory/tegra/tegra124-emc.c
index ee8ee39e98ed..edfbf6d6d357 100644
--- a/drivers/memory/tegra/tegra124-emc.c
+++ b/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)
@@ -1226,9 +1228,19 @@ 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;
 };
 
@@ -1240,9 +1252,8 @@ 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 <mperttu...@nvidia.com>");
+MODULE_DESCRIPTION("NVIDIA Tegra124 EMC driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/clk/tegra.h b/include/linux/clk/tegra.h
index 3f01d43f0598..eb016fc9cc0b 100644
--- a/include/linux/clk/tegra.h
+++ b/include/linux/clk/tegra.h
@@ -136,6 +136,7 @@ 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 tegra_emc;
 
 typedef long (tegra20_clk_emc_round_cb)(unsigned long rate,
                                        unsigned long min_rate,
@@ -146,6 +147,13 @@ 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;
diff --git a/include/soc/tegra/emc.h b/include/soc/tegra/emc.h
deleted file mode 100644
index 05199a97ccf4..000000000000
--- a/include/soc/tegra/emc.h
+++ /dev/null
@@ -1,16 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright (c) 2014 NVIDIA Corporation. All rights reserved.
- */
-
-#ifndef __SOC_TEGRA_EMC_H__
-#define __SOC_TEGRA_EMC_H__
-
-struct tegra_emc;
-
-int tegra_emc_prepare_timing_change(struct tegra_emc *emc,
-                                   unsigned long rate);
-void tegra_emc_complete_timing_change(struct tegra_emc *emc,
-                                     unsigned long rate);
-
-#endif /* __SOC_TEGRA_EMC_H__ */
-- 
2.29.2

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