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path: root/drivers/clk/tegra/clk-emc.c
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-rw-r--r--drivers/clk/tegra/clk-emc.c539
1 files changed, 539 insertions, 0 deletions
diff --git a/drivers/clk/tegra/clk-emc.c b/drivers/clk/tegra/clk-emc.c
new file mode 100644
index 000000000..7aeace88b
--- /dev/null
+++ b/drivers/clk/tegra/clk-emc.c
@@ -0,0 +1,539 @@
+/*
+ * drivers/clk/tegra/clk-emc.c
+ *
+ * Copyright (c) 2014, NVIDIA CORPORATION. All rights reserved.
+ *
+ * Author:
+ * Mikko Perttunen <mperttunen@nvidia.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/delay.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;
+
+ tegra = container_of(hw, struct tegra_clk_emc, hw);
+
+ for (i = 0; i < tegra->num_timings; i++) {
+ if (tegra->timings[i].ram_code != ram_code)
+ continue;
+
+ timing = tegra->timings + i;
+
+ if (timing->rate > req->max_rate) {
+ i = max(i, 1);
+ req->rate = tegra->timings[i - 1].rate;
+ return 0;
+ }
+
+ if (timing->rate < req->min_rate)
+ continue;
+
+ if (timing->rate >= req->rate) {
+ 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) {
+ put_device(&pdev->dev);
+ 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) {
+ BUG();
+ 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)
+ continue;
+
+ 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)
+ continue;
+
+ 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;
+ for (i = 0; i < ARRAY_SIZE(emc_parent_clk_names); i++) {
+ if (!strcmp(emc_parent_clk_names[i],
+ __clk_get_name(timing->parent))) {
+ timing->parent_index = i;
+ break;
+ }
+ }
+ if (timing->parent_index == 0xff) {
+ pr_err("timing %pOF: %s is not a valid parent\n",
+ node, __clk_get_name(timing->parent));
+ clk_put(timing->parent);
+ return -EINVAL;
+ }
+
+ 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 device_node *child;
+ int child_count = of_get_child_count(node);
+ int i = 0, err;
+
+ tegra->timings = kcalloc(child_count, sizeof(struct emc_timing),
+ GFP_KERNEL);
+ if (!tegra->timings)
+ return -ENOMEM;
+
+ tegra->num_timings = child_count;
+
+ for_each_child_of_node(node, child) {
+ struct emc_timing *timing = tegra->timings + (i++);
+
+ err = load_one_timing_from_dt(tegra, timing, child);
+ if (err) {
+ of_node_put(child);
+ return err;
+ }
+
+ timing->ram_code = ram_code;
+ }
+
+ sort(tegra->timings, tegra->num_timings, 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);
+ of_node_put(node);
+ if (err)
+ return ERR_PTR(err);
+ break;
+ }
+
+ 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");
+
+ clk_prepare_enable(clk);
+
+ return clk;
+};
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