1 files changed, 540 insertions, 0 deletions
diff --git a/drivers/clk/tegra/clk-tegra124-emc.c b/drivers/clk/tegra/clk-tegra124-emc.c
new file mode 100644
index 000000000000..745f9faa98d8
--- /dev/null
+++ b/drivers/clk/tegra/clk-tegra124-emc.c
@@ -0,0 +1,540 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * drivers/clk/tegra/clk-emc.c
+ *
+ * Copyright (c) 2014, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * Author:
+ *	Mikko Perttunen <mperttunen@nvidia.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clk.h>
+#include <linux/clkdev.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/fuse.h>
+#include <soc/tegra/emc.h>
+
+#include "clk.h"
+
+#define CLK_SOURCE_EMC 0x19c
+
+#define CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_SHIFT 0
+#define CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_MASK 0xff
+#define CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR(x) (((x) & CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_MASK) << \
+					      CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_SHIFT)
+
+#define CLK_SOURCE_EMC_EMC_2X_CLK_SRC_SHIFT 29
+#define CLK_SOURCE_EMC_EMC_2X_CLK_SRC_MASK 0x7
+#define CLK_SOURCE_EMC_EMC_2X_CLK_SRC(x) (((x) & CLK_SOURCE_EMC_EMC_2X_CLK_SRC_MASK) << \
+					  CLK_SOURCE_EMC_EMC_2X_CLK_SRC_SHIFT)
+
+static const char * const emc_parent_clk_names[] = {
+	"pll_m", "pll_c", "pll_p", "clk_m", "pll_m_ud",
+	"pll_c2", "pll_c3", "pll_c_ud"
+};
+
+/*
+ * List of clock sources for various parents the EMC clock can have.
+ * When we change the timing to a timing with a parent that has the same
+ * clock source as the current parent, we must first change to a backup
+ * timing that has a different clock source.
+ */
+
+#define EMC_SRC_PLL_M 0
+#define EMC_SRC_PLL_C 1
+#define EMC_SRC_PLL_P 2
+#define EMC_SRC_CLK_M 3
+#define EMC_SRC_PLL_C2 4
+#define EMC_SRC_PLL_C3 5
+
+static const char emc_parent_clk_sources[] = {
+	EMC_SRC_PLL_M, EMC_SRC_PLL_C, EMC_SRC_PLL_P, EMC_SRC_CLK_M,
+	EMC_SRC_PLL_M, EMC_SRC_PLL_C2, EMC_SRC_PLL_C3, EMC_SRC_PLL_C
+};
+
+struct emc_timing {
+	unsigned long rate, parent_rate;
+	u8 parent_index;
+	struct clk *parent;
+	u32 ram_code;
+};
+
+struct tegra_clk_emc {
+	struct clk_hw hw;
+	void __iomem *clk_regs;
+	struct clk *prev_parent;
+	bool changing_timing;
+
+	struct device_node *emc_node;
+	struct tegra_emc *emc;
+
+	int num_timings;
+	struct emc_timing *timings;
+	spinlock_t *lock;
+};
+
+/* Common clock framework callback implementations */
+
+static unsigned long emc_recalc_rate(struct clk_hw *hw,
+				     unsigned long parent_rate)
+{
+	struct tegra_clk_emc *tegra;
+	u32 val, div;
+
+	tegra = container_of(hw, struct tegra_clk_emc, hw);
+
+	/*
+	 * CCF wrongly assumes that the parent won't change during set_rate,
+	 * so get the parent rate explicitly.
+	 */
+	parent_rate = clk_hw_get_rate(clk_hw_get_parent(hw));
+
+	val = readl(tegra->clk_regs + CLK_SOURCE_EMC);
+	div = val & CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_MASK;
+
+	return parent_rate / (div + 2) * 2;
+}
+
+/*
+ * Rounds up unless no higher rate exists, in which case down. This way is
+ * safer since things have EMC rate floors. Also don't touch parent_rate
+ * since we don't want the CCF to play with our parent clocks.
+ */
+static int emc_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
+{
+	struct tegra_clk_emc *tegra;
+	u8 ram_code = tegra_read_ram_code();
+	struct emc_timing *timing = NULL;
+	int i, k, t;
+
+	tegra = container_of(hw, struct tegra_clk_emc, hw);
+
+	for (k = 0; k < tegra->num_timings; k++) {
+		if (tegra->timings[k].ram_code == ram_code)
+			break;
+	}
+
+	for (t = k; t < tegra->num_timings; t++) {
+		if (tegra->timings[t].ram_code != ram_code)
+			break;
+	}
+
+	for (i = k; i < t; i++) {
+		timing = tegra->timings + i;
+
+		if (timing->rate < req->rate && i != t - 1)
+			continue;
+
+		if (timing->rate > req->max_rate) {
+			i = max(i, k + 1);
+			req->rate = tegra->timings[i - 1].rate;
+			return 0;
+		}
+
+		if (timing->rate < req->min_rate)
+			continue;
+
+		req->rate = timing->rate;
+		return 0;
+	}
+
+	if (timing) {
+		req->rate = timing->rate;
+		return 0;
+	}
+
+	req->rate = clk_hw_get_rate(hw);
+	return 0;
+}
+
+static u8 emc_get_parent(struct clk_hw *hw)
+{
+	struct tegra_clk_emc *tegra;
+	u32 val;
+
+	tegra = container_of(hw, struct tegra_clk_emc, hw);
+
+	val = readl(tegra->clk_regs + CLK_SOURCE_EMC);
+
+	return (val >> CLK_SOURCE_EMC_EMC_2X_CLK_SRC_SHIFT)
+		& CLK_SOURCE_EMC_EMC_2X_CLK_SRC_MASK;
+}
+
+static struct tegra_emc *emc_ensure_emc_driver(struct tegra_clk_emc *tegra)
+{
+	struct platform_device *pdev;
+
+	if (tegra->emc)
+		return tegra->emc;
+
+	if (!tegra->emc_node)
+		return NULL;
+
+	pdev = of_find_device_by_node(tegra->emc_node);
+	if (!pdev) {
+		pr_err("%s: could not get external memory controller\n",
+		       __func__);
+		return NULL;
+	}
+
+	of_node_put(tegra->emc_node);
+	tegra->emc_node = NULL;
+
+	tegra->emc = platform_get_drvdata(pdev);
+	if (!tegra->emc) {
+		pr_err("%s: cannot find EMC driver\n", __func__);
+		return NULL;
+	}
+
+	return tegra->emc;
+}
+
+static int emc_set_timing(struct tegra_clk_emc *tegra,
+			  struct emc_timing *timing)
+{
+	int err;
+	u8 div;
+	u32 car_value;
+	unsigned long flags = 0;
+	struct tegra_emc *emc = emc_ensure_emc_driver(tegra);
+
+	if (!emc)
+		return -ENOENT;
+
+	pr_debug("going to rate %ld prate %ld p %s\n", timing->rate,
+		 timing->parent_rate, __clk_get_name(timing->parent));
+
+	if (emc_get_parent(&tegra->hw) == timing->parent_index &&
+	    clk_get_rate(timing->parent) != timing->parent_rate) {
+		WARN_ONCE(1, "parent %s rate mismatch %lu %lu\n",
+			  __clk_get_name(timing->parent),
+			  clk_get_rate(timing->parent),
+			  timing->parent_rate);
+		return -EINVAL;
+	}
+
+	tegra->changing_timing = true;
+
+	err = clk_set_rate(timing->parent, timing->parent_rate);
+	if (err) {
+		pr_err("cannot change parent %s rate to %ld: %d\n",
+		       __clk_get_name(timing->parent), timing->parent_rate,
+		       err);
+
+		return err;
+	}
+
+	err = clk_prepare_enable(timing->parent);
+	if (err) {
+		pr_err("cannot enable parent clock: %d\n", err);
+		return err;
+	}
+
+	div = timing->parent_rate / (timing->rate / 2) - 2;
+
+	err = tegra_emc_prepare_timing_change(emc, timing->rate);
+	if (err)
+		return err;
+
+	spin_lock_irqsave(tegra->lock, flags);
+
+	car_value = readl(tegra->clk_regs + CLK_SOURCE_EMC);
+
+	car_value &= ~CLK_SOURCE_EMC_EMC_2X_CLK_SRC(~0);
+	car_value |= CLK_SOURCE_EMC_EMC_2X_CLK_SRC(timing->parent_index);
+
+	car_value &= ~CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR(~0);
+	car_value |= CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR(div);
+
+	writel(car_value, tegra->clk_regs + CLK_SOURCE_EMC);
+
+	spin_unlock_irqrestore(tegra->lock, flags);
+
+	tegra_emc_complete_timing_change(emc, timing->rate);
+
+	clk_hw_reparent(&tegra->hw, __clk_get_hw(timing->parent));
+	clk_disable_unprepare(tegra->prev_parent);
+
+	tegra->prev_parent = timing->parent;
+	tegra->changing_timing = false;
+
+	return 0;
+}
+
+/*
+ * Get backup timing to use as an intermediate step when a change between
+ * two timings with the same clock source has been requested. First try to
+ * find a timing with a higher clock rate to avoid a rate below any set rate
+ * floors. If that is not possible, find a lower rate.
+ */
+static struct emc_timing *get_backup_timing(struct tegra_clk_emc *tegra,
+					    int timing_index)
+{
+	int i;
+	u32 ram_code = tegra_read_ram_code();
+	struct emc_timing *timing;
+
+	for (i = timing_index+1; i < tegra->num_timings; i++) {
+		timing = tegra->timings + i;
+		if (timing->ram_code != ram_code)
+			break;
+
+		if (emc_parent_clk_sources[timing->parent_index] !=
+		    emc_parent_clk_sources[
+		      tegra->timings[timing_index].parent_index])
+			return timing;
+	}
+
+	for (i = timing_index-1; i >= 0; --i) {
+		timing = tegra->timings + i;
+		if (timing->ram_code != ram_code)
+			break;
+
+		if (emc_parent_clk_sources[timing->parent_index] !=
+		    emc_parent_clk_sources[
+		      tegra->timings[timing_index].parent_index])
+			return timing;
+	}
+
+	return NULL;
+}
+
+static int emc_set_rate(struct clk_hw *hw, unsigned long rate,
+			unsigned long parent_rate)
+{
+	struct tegra_clk_emc *tegra;
+	struct emc_timing *timing = NULL;
+	int i, err;
+	u32 ram_code = tegra_read_ram_code();
+
+	tegra = container_of(hw, struct tegra_clk_emc, hw);
+
+	if (clk_hw_get_rate(hw) == rate)
+		return 0;
+
+	/*
+	 * When emc_set_timing changes the parent rate, CCF will propagate
+	 * that downward to us, so ignore any set_rate calls while a rate
+	 * change is already going on.
+	 */
+	if (tegra->changing_timing)
+		return 0;
+
+	for (i = 0; i < tegra->num_timings; i++) {
+		if (tegra->timings[i].rate == rate &&
+		    tegra->timings[i].ram_code == ram_code) {
+			timing = tegra->timings + i;
+			break;
+		}
+	}
+
+	if (!timing) {
+		pr_err("cannot switch to rate %ld without emc table\n", rate);
+		return -EINVAL;
+	}
+
+	if (emc_parent_clk_sources[emc_get_parent(hw)] ==
+	    emc_parent_clk_sources[timing->parent_index] &&
+	    clk_get_rate(timing->parent) != timing->parent_rate) {
+		/*
+		 * Parent clock source not changed but parent rate has changed,
+		 * need to temporarily switch to another parent
+		 */
+
+		struct emc_timing *backup_timing;
+
+		backup_timing = get_backup_timing(tegra, i);
+		if (!backup_timing) {
+			pr_err("cannot find backup timing\n");
+			return -EINVAL;
+		}
+
+		pr_debug("using %ld as backup rate when going to %ld\n",
+			 backup_timing->rate, rate);
+
+		err = emc_set_timing(tegra, backup_timing);
+		if (err) {
+			pr_err("cannot set backup timing: %d\n", err);
+			return err;
+		}
+	}
+
+	return emc_set_timing(tegra, timing);
+}
+
+/* Initialization and deinitialization */
+
+static int load_one_timing_from_dt(struct tegra_clk_emc *tegra,
+				   struct emc_timing *timing,
+				   struct device_node *node)
+{
+	int err, i;
+	u32 tmp;
+
+	err = of_property_read_u32(node, "clock-frequency", &tmp);
+	if (err) {
+		pr_err("timing %pOF: failed to read rate\n", node);
+		return err;
+	}
+
+	timing->rate = tmp;
+
+	err = of_property_read_u32(node, "nvidia,parent-clock-frequency", &tmp);
+	if (err) {
+		pr_err("timing %pOF: failed to read parent rate\n", node);
+		return err;
+	}
+
+	timing->parent_rate = tmp;
+
+	timing->parent = of_clk_get_by_name(node, "emc-parent");
+	if (IS_ERR(timing->parent)) {
+		pr_err("timing %pOF: failed to get parent clock\n", node);
+		return PTR_ERR(timing->parent);
+	}
+
+	timing->parent_index = 0xff;
+	i = match_string(emc_parent_clk_names, ARRAY_SIZE(emc_parent_clk_names),
+			 __clk_get_name(timing->parent));
+	if (i < 0) {
+		pr_err("timing %pOF: %s is not a valid parent\n",
+		       node, __clk_get_name(timing->parent));
+		clk_put(timing->parent);
+		return -EINVAL;
+	}
+
+	timing->parent_index = i;
+	return 0;
+}
+
+static int cmp_timings(const void *_a, const void *_b)
+{
+	const struct emc_timing *a = _a;
+	const struct emc_timing *b = _b;
+
+	if (a->rate < b->rate)
+		return -1;
+	else if (a->rate == b->rate)
+		return 0;
+	else
+		return 1;
+}
+
+static int load_timings_from_dt(struct tegra_clk_emc *tegra,
+				struct device_node *node,
+				u32 ram_code)
+{
+	struct emc_timing *timings_ptr;
+	struct device_node *child;
+	int child_count = of_get_child_count(node);
+	int i = 0, err;
+	size_t size;
+
+	size = (tegra->num_timings + child_count) * sizeof(struct emc_timing);
+
+	tegra->timings = krealloc(tegra->timings, size, GFP_KERNEL);
+	if (!tegra->timings)
+		return -ENOMEM;
+
+	timings_ptr = tegra->timings + tegra->num_timings;
+	tegra->num_timings += child_count;
+
+	for_each_child_of_node(node, child) {
+		struct emc_timing *timing = timings_ptr + (i++);
+
+		err = load_one_timing_from_dt(tegra, timing, child);
+		if (err) {
+			of_node_put(child);
+			return err;
+		}
+
+		timing->ram_code = ram_code;
+	}
+
+	sort(timings_ptr, child_count, sizeof(struct emc_timing),
+	     cmp_timings, NULL);
+
+	return 0;
+}
+
+static const struct clk_ops tegra_clk_emc_ops = {
+	.recalc_rate = emc_recalc_rate,
+	.determine_rate = emc_determine_rate,
+	.set_rate = emc_set_rate,
+	.get_parent = emc_get_parent,
+};
+
+struct clk *tegra_clk_register_emc(void __iomem *base, struct device_node *np,
+				   spinlock_t *lock)
+{
+	struct tegra_clk_emc *tegra;
+	struct clk_init_data init;
+	struct device_node *node;
+	u32 node_ram_code;
+	struct clk *clk;
+	int err;
+
+	tegra = kcalloc(1, sizeof(*tegra), GFP_KERNEL);
+	if (!tegra)
+		return ERR_PTR(-ENOMEM);
+
+	tegra->clk_regs = base;
+	tegra->lock = lock;
+
+	tegra->num_timings = 0;
+
+	for_each_child_of_node(np, node) {
+		err = of_property_read_u32(node, "nvidia,ram-code",
+					   &node_ram_code);
+		if (err)
+			continue;
+
+		/*
+		 * Store timings for all ram codes as we cannot read the
+		 * fuses until the apbmisc driver is loaded.
+		 */
+		err = load_timings_from_dt(tegra, node, node_ram_code);
+		if (err) {
+			of_node_put(node);
+			return ERR_PTR(err);
+		}
+	}
+
+	if (tegra->num_timings == 0)
+		pr_warn("%s: no memory timings registered\n", __func__);
+
+	tegra->emc_node = of_parse_phandle(np,
+			"nvidia,external-memory-controller", 0);
+	if (!tegra->emc_node)
+		pr_warn("%s: couldn't find node for EMC driver\n", __func__);
+
+	init.name = "emc";
+	init.ops = &tegra_clk_emc_ops;
+	init.flags = CLK_IS_CRITICAL;
+	init.parent_names = emc_parent_clk_names;
+	init.num_parents = ARRAY_SIZE(emc_parent_clk_names);
+
+	tegra->hw.init = &init;
+
+	clk = clk_register(NULL, &tegra->hw);
+	if (IS_ERR(clk))
+		return clk;
+
+	tegra->prev_parent = clk_hw_get_parent_by_index(
+		&tegra->hw, emc_get_parent(&tegra->hw))->clk;
+	tegra->changing_timing = false;
+
+	/* Allow debugging tools to see the EMC clock */
+	clk_register_clkdev(clk, "emc", "tegra-clk-debug");
+
+	return clk;
+};