1 files changed, 371 insertions, 0 deletions
diff --git a/drivers/clk/tegra/clk-tegra210-emc.c b/drivers/clk/tegra/clk-tegra210-emc.c
new file mode 100644
index 000000000..672ca8c18
--- /dev/null
+++ b/drivers/clk/tegra/clk-tegra210-emc.c
@@ -0,0 +1,371 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2015-2020, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/clk/tegra.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+
+#include "clk.h"
+
+#define CLK_SOURCE_EMC 0x19c
+#define  CLK_SOURCE_EMC_2X_CLK_SRC GENMASK(31, 29)
+#define  CLK_SOURCE_EMC_MC_EMC_SAME_FREQ BIT(16)
+#define  CLK_SOURCE_EMC_2X_CLK_DIVISOR GENMASK(7, 0)
+
+#define CLK_SRC_PLLM 0
+#define CLK_SRC_PLLC 1
+#define CLK_SRC_PLLP 2
+#define CLK_SRC_CLK_M 3
+#define CLK_SRC_PLLM_UD 4
+#define CLK_SRC_PLLMB_UD 5
+#define CLK_SRC_PLLMB 6
+#define CLK_SRC_PLLP_UD 7
+
+struct tegra210_clk_emc {
+	struct clk_hw hw;
+	void __iomem *regs;
+
+	struct tegra210_clk_emc_provider *provider;
+
+	struct clk *parents[8];
+};
+
+static inline struct tegra210_clk_emc *
+to_tegra210_clk_emc(struct clk_hw *hw)
+{
+	return container_of(hw, struct tegra210_clk_emc, hw);
+}
+
+static const char *tegra210_clk_emc_parents[] = {
+	"pll_m", "pll_c", "pll_p", "clk_m", "pll_m_ud", "pll_mb_ud",
+	"pll_mb", "pll_p_ud",
+};
+
+static u8 tegra210_clk_emc_get_parent(struct clk_hw *hw)
+{
+	struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw);
+	u32 value;
+	u8 src;
+
+	value = readl_relaxed(emc->regs + CLK_SOURCE_EMC);
+	src = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_SRC, value);
+
+	return src;
+}
+
+static unsigned long tegra210_clk_emc_recalc_rate(struct clk_hw *hw,
+						  unsigned long parent_rate)
+{
+	struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw);
+	u32 value, div;
+
+	/*
+	 * CCF assumes that neither the parent nor its rate will change during
+	 * ->set_rate(), so the parent rate passed in here was cached from the
+	 * parent before the ->set_rate() call.
+	 *
+	 * This can lead to wrong results being reported for the EMC clock if
+	 * the parent and/or parent rate have changed as part of the EMC rate
+	 * change sequence. Fix this by overriding the parent clock with what
+	 * we know to be the correct value after the rate change.
+	 */
+	parent_rate = clk_hw_get_rate(clk_hw_get_parent(hw));
+
+	value = readl_relaxed(emc->regs + CLK_SOURCE_EMC);
+
+	div = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_DIVISOR, value);
+	div += 2;
+
+	return DIV_ROUND_UP(parent_rate * 2, div);
+}
+
+static long tegra210_clk_emc_round_rate(struct clk_hw *hw, unsigned long rate,
+					unsigned long *prate)
+{
+	struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw);
+	struct tegra210_clk_emc_provider *provider = emc->provider;
+	unsigned int i;
+
+	if (!provider || !provider->configs || provider->num_configs == 0)
+		return clk_hw_get_rate(hw);
+
+	for (i = 0; i < provider->num_configs; i++) {
+		if (provider->configs[i].rate >= rate)
+			return provider->configs[i].rate;
+	}
+
+	return provider->configs[i - 1].rate;
+}
+
+static struct clk *tegra210_clk_emc_find_parent(struct tegra210_clk_emc *emc,
+						u8 index)
+{
+	struct clk_hw *parent = clk_hw_get_parent_by_index(&emc->hw, index);
+	const char *name = clk_hw_get_name(parent);
+
+	/* XXX implement cache? */
+
+	return __clk_lookup(name);
+}
+
+static int tegra210_clk_emc_set_rate(struct clk_hw *hw, unsigned long rate,
+				     unsigned long parent_rate)
+{
+	struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw);
+	struct tegra210_clk_emc_provider *provider = emc->provider;
+	struct tegra210_clk_emc_config *config;
+	struct device *dev = provider->dev;
+	struct clk_hw *old, *new, *parent;
+	u8 old_idx, new_idx, index;
+	struct clk *clk;
+	unsigned int i;
+	int err;
+
+	if (!provider->configs || provider->num_configs == 0)
+		return -EINVAL;
+
+	for (i = 0; i < provider->num_configs; i++) {
+		if (provider->configs[i].rate >= rate) {
+			config = &provider->configs[i];
+			break;
+		}
+	}
+
+	if (i == provider->num_configs)
+		config = &provider->configs[i - 1];
+
+	old_idx = tegra210_clk_emc_get_parent(hw);
+	new_idx = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_SRC, config->value);
+
+	old = clk_hw_get_parent_by_index(hw, old_idx);
+	new = clk_hw_get_parent_by_index(hw, new_idx);
+
+	/* if the rate has changed... */
+	if (config->parent_rate != clk_hw_get_rate(old)) {
+		/* ... but the clock source remains the same ... */
+		if (new_idx == old_idx) {
+			/* ... switch to the alternative clock source. */
+			switch (new_idx) {
+			case CLK_SRC_PLLM:
+				new_idx = CLK_SRC_PLLMB;
+				break;
+
+			case CLK_SRC_PLLM_UD:
+				new_idx = CLK_SRC_PLLMB_UD;
+				break;
+
+			case CLK_SRC_PLLMB_UD:
+				new_idx = CLK_SRC_PLLM_UD;
+				break;
+
+			case CLK_SRC_PLLMB:
+				new_idx = CLK_SRC_PLLM;
+				break;
+			}
+
+			/*
+			 * This should never happen because we can't deal with
+			 * it.
+			 */
+			if (WARN_ON(new_idx == old_idx))
+				return -EINVAL;
+
+			new = clk_hw_get_parent_by_index(hw, new_idx);
+		}
+
+		index = new_idx;
+		parent = new;
+	} else {
+		index = old_idx;
+		parent = old;
+	}
+
+	clk = tegra210_clk_emc_find_parent(emc, index);
+	if (IS_ERR(clk)) {
+		err = PTR_ERR(clk);
+		dev_err(dev, "failed to get parent clock for index %u: %d\n",
+			index, err);
+		return err;
+	}
+
+	/* set the new parent clock to the required rate */
+	if (clk_get_rate(clk) != config->parent_rate) {
+		err = clk_set_rate(clk, config->parent_rate);
+		if (err < 0) {
+			dev_err(dev, "failed to set rate %lu Hz for %pC: %d\n",
+				config->parent_rate, clk, err);
+			return err;
+		}
+	}
+
+	/* enable the new parent clock */
+	if (parent != old) {
+		err = clk_prepare_enable(clk);
+		if (err < 0) {
+			dev_err(dev, "failed to enable parent clock %pC: %d\n",
+				clk, err);
+			return err;
+		}
+	}
+
+	/* update the EMC source configuration to reflect the new parent */
+	config->value &= ~CLK_SOURCE_EMC_2X_CLK_SRC;
+	config->value |= FIELD_PREP(CLK_SOURCE_EMC_2X_CLK_SRC, index);
+
+	/*
+	 * Finally, switch the EMC programming with both old and new parent
+	 * clocks enabled.
+	 */
+	err = provider->set_rate(dev, config);
+	if (err < 0) {
+		dev_err(dev, "failed to set EMC rate to %lu Hz: %d\n", rate,
+			err);
+
+		/*
+		 * If we're unable to switch to the new EMC frequency, we no
+		 * longer need the new parent to be enabled.
+		 */
+		if (parent != old)
+			clk_disable_unprepare(clk);
+
+		return err;
+	}
+
+	/* reparent to new parent clock and disable the old parent clock */
+	if (parent != old) {
+		clk = tegra210_clk_emc_find_parent(emc, old_idx);
+		if (IS_ERR(clk)) {
+			err = PTR_ERR(clk);
+			dev_err(dev,
+				"failed to get parent clock for index %u: %d\n",
+				old_idx, err);
+			return err;
+		}
+
+		clk_hw_reparent(hw, parent);
+		clk_disable_unprepare(clk);
+	}
+
+	return err;
+}
+
+static const struct clk_ops tegra210_clk_emc_ops = {
+	.get_parent = tegra210_clk_emc_get_parent,
+	.recalc_rate = tegra210_clk_emc_recalc_rate,
+	.round_rate = tegra210_clk_emc_round_rate,
+	.set_rate = tegra210_clk_emc_set_rate,
+};
+
+struct clk *tegra210_clk_register_emc(struct device_node *np,
+				      void __iomem *regs)
+{
+	struct tegra210_clk_emc *emc;
+	struct clk_init_data init;
+	struct clk *clk;
+
+	emc = kzalloc(sizeof(*emc), GFP_KERNEL);
+	if (!emc)
+		return ERR_PTR(-ENOMEM);
+
+	emc->regs = regs;
+
+	init.name = "emc";
+	init.ops = &tegra210_clk_emc_ops;
+	init.flags = CLK_IS_CRITICAL | CLK_GET_RATE_NOCACHE;
+	init.parent_names = tegra210_clk_emc_parents;
+	init.num_parents = ARRAY_SIZE(tegra210_clk_emc_parents);
+	emc->hw.init = &init;
+
+	clk = clk_register(NULL, &emc->hw);
+	if (IS_ERR(clk)) {
+		kfree(emc);
+		return clk;
+	}
+
+	return clk;
+}
+
+int tegra210_clk_emc_attach(struct clk *clk,
+			    struct tegra210_clk_emc_provider *provider)
+{
+	struct clk_hw *hw = __clk_get_hw(clk);
+	struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw);
+	struct device *dev = provider->dev;
+	unsigned int i;
+	int err;
+
+	if (!try_module_get(provider->owner))
+		return -ENODEV;
+
+	for (i = 0; i < provider->num_configs; i++) {
+		struct tegra210_clk_emc_config *config = &provider->configs[i];
+		struct clk_hw *parent;
+		bool same_freq;
+		u8 div, src;
+
+		div = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_DIVISOR, config->value);
+		src = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_SRC, config->value);
+
+		/* do basic sanity checking on the EMC timings */
+		if (div & 0x1) {
+			dev_err(dev, "invalid odd divider %u for rate %lu Hz\n",
+				div, config->rate);
+			err = -EINVAL;
+			goto put;
+		}
+
+		same_freq = config->value & CLK_SOURCE_EMC_MC_EMC_SAME_FREQ;
+
+		if (same_freq != config->same_freq) {
+			dev_err(dev,
+				"ambiguous EMC to MC ratio for rate %lu Hz\n",
+				config->rate);
+			err = -EINVAL;
+			goto put;
+		}
+
+		parent = clk_hw_get_parent_by_index(hw, src);
+		config->parent = src;
+
+		if (src == CLK_SRC_PLLM || src == CLK_SRC_PLLM_UD) {
+			config->parent_rate = config->rate * (1 + div / 2);
+		} else {
+			unsigned long rate = config->rate * (1 + div / 2);
+
+			config->parent_rate = clk_hw_get_rate(parent);
+
+			if (config->parent_rate != rate) {
+				dev_err(dev,
+					"rate %lu Hz does not match input\n",
+					config->rate);
+				err = -EINVAL;
+				goto put;
+			}
+		}
+	}
+
+	emc->provider = provider;
+
+	return 0;
+
+put:
+	module_put(provider->owner);
+	return err;
+}
+EXPORT_SYMBOL_GPL(tegra210_clk_emc_attach);
+
+void tegra210_clk_emc_detach(struct clk *clk)
+{
+	struct tegra210_clk_emc *emc = to_tegra210_clk_emc(__clk_get_hw(clk));
+
+	module_put(emc->provider->owner);
+	emc->provider = NULL;
+}
+EXPORT_SYMBOL_GPL(tegra210_clk_emc_detach);