[ARM] tegra: Add clock support

v2: fixes from Russell King:
	- include linux/io.h instead of asm/io.h
	- fix whitespace in Kconfig
	- Use spin_lock_init to initialize lock
	- Return -ENOSYS instead of BUG for unimplemented clock ops
	- Use proper return values in tegra2 clock ops
    additional changes:
	- Rename some clocks to match dev_ids
	- add rate propagation
	- add debugfs entries
	- add support for clock listed in clk_lookup under multiple dev_ids
v3:
	- Replace per-clock locking with global clock lock
	- Autodetect clock state on init
	- Let clock dividers pick next lower possible frequency
	- Add support for clock init tables
	- Minor bug fixes
	- Fix checkpatch issues

Signed-off-by: Colin Cross <ccross@android.com>

1 files changed, 488 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/clock.c b/arch/arm/mach-tegra/clock.c
new file mode 100644
index 000000000000..03ad578349b9
--- /dev/null
+++ b/arch/arm/mach-tegra/clock.c
@@ -0,0 +1,488 @@
+/*
+ *
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ *      Colin Cross <ccross@google.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/kernel.h>
+#include <linux/clk.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <asm/clkdev.h>
+
+#include "clock.h"
+
+static LIST_HEAD(clocks);
+
+static DEFINE_SPINLOCK(clock_lock);
+
+struct clk *tegra_get_clock_by_name(const char *name)
+{
+        struct clk *c;
+        struct clk *ret = NULL;
+        unsigned long flags;
+        spin_lock_irqsave(&clock_lock, flags);
+        list_for_each_entry(c, &clocks, node) {
+                if (strcmp(c->name, name) == 0) {
+                        ret = c;
+                        break;
+                }
+        }
+        spin_unlock_irqrestore(&clock_lock, flags);
+        return ret;
+}
+
+int clk_reparent(struct clk *c, struct clk *parent)
+{
+        pr_debug("%s: %s\n", __func__, c->name);
+        if (c->refcnt && c->parent)
+                clk_disable_locked(c->parent);
+        c->parent = parent;
+        if (c->refcnt && c->parent)
+                clk_enable_locked(c->parent);
+        list_del(&c->sibling);
+        list_add_tail(&c->sibling, &parent->children);
+        return 0;
+}
+
+static void propagate_rate(struct clk *c)
+{
+        struct clk *clkp;
+        pr_debug("%s: %s\n", __func__, c->name);
+        list_for_each_entry(clkp, &c->children, sibling) {
+                pr_debug("   %s\n", clkp->name);
+                if (clkp->ops->recalculate_rate)
+                        clkp->ops->recalculate_rate(clkp);
+                propagate_rate(clkp);
+        }
+}
+
+void clk_init(struct clk *c)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&clock_lock, flags);
+
+        INIT_LIST_HEAD(&c->children);
+        INIT_LIST_HEAD(&c->sibling);
+
+        if (c->ops && c->ops->init)
+                c->ops->init(c);
+
+        list_add(&c->node, &clocks);
+
+        if (c->parent)
+                list_add_tail(&c->sibling, &c->parent->children);
+
+        spin_unlock_irqrestore(&clock_lock, flags);
+}
+
+int clk_enable_locked(struct clk *c)
+{
+        int ret;
+        pr_debug("%s: %s\n", __func__, c->name);
+        if (c->refcnt == 0) {
+                if (c->parent) {
+                        ret = clk_enable_locked(c->parent);
+                        if (ret)
+                                return ret;
+                }
+
+                if (c->ops && c->ops->enable) {
+                        ret = c->ops->enable(c);
+                        if (ret) {
+                                if (c->parent)
+                                        clk_disable_locked(c->parent);
+                                return ret;
+                        }
+                        c->state = ON;
+#ifdef CONFIG_DEBUG_FS
+                        c->set = 1;
+#endif
+                }
+        }
+        c->refcnt++;
+
+        return 0;
+}
+
+int clk_enable(struct clk *c)
+{
+        int ret;
+        unsigned long flags;
+        spin_lock_irqsave(&clock_lock, flags);
+        ret = clk_enable_locked(c);
+        spin_unlock_irqrestore(&clock_lock, flags);
+        return ret;
+}
+EXPORT_SYMBOL(clk_enable);
+
+void clk_disable_locked(struct clk *c)
+{
+        pr_debug("%s: %s\n", __func__, c->name);
+        if (c->refcnt == 0) {
+                WARN(1, "Attempting to disable clock %s with refcnt 0", c->name);
+                return;
+        }
+        if (c->refcnt == 1) {
+                if (c->ops && c->ops->disable)
+                        c->ops->disable(c);
+
+                if (c->parent)
+                        clk_disable_locked(c->parent);
+
+                c->state = OFF;
+        }
+        c->refcnt--;
+}
+
+void clk_disable(struct clk *c)
+{
+        unsigned long flags;
+        spin_lock_irqsave(&clock_lock, flags);
+        clk_disable_locked(c);
+        spin_unlock_irqrestore(&clock_lock, flags);
+}
+EXPORT_SYMBOL(clk_disable);
+
+int clk_set_parent_locked(struct clk *c, struct clk *parent)
+{
+        int ret;
+
+        pr_debug("%s: %s\n", __func__, c->name);
+
+        if (!c->ops || !c->ops->set_parent)
+                return -ENOSYS;
+
+        ret = c->ops->set_parent(c, parent);
+
+        if (ret)
+                return ret;
+
+        propagate_rate(c);
+
+        return 0;
+}
+
+int clk_set_parent(struct clk *c, struct clk *parent)
+{
+        int ret;
+        unsigned long flags;
+        spin_lock_irqsave(&clock_lock, flags);
+        ret = clk_set_parent_locked(c, parent);
+        spin_unlock_irqrestore(&clock_lock, flags);
+        return ret;
+}
+EXPORT_SYMBOL(clk_set_parent);
+
+struct clk *clk_get_parent(struct clk *c)
+{
+        return c->parent;
+}
+EXPORT_SYMBOL(clk_get_parent);
+
+int clk_set_rate(struct clk *c, unsigned long rate)
+{
+        int ret = 0;
+        unsigned long flags;
+
+        spin_lock_irqsave(&clock_lock, flags);
+
+        pr_debug("%s: %s\n", __func__, c->name);
+
+        if (c->ops && c->ops->set_rate)
+                ret = c->ops->set_rate(c, rate);
+        else
+                ret = -ENOSYS;
+
+        propagate_rate(c);
+
+        spin_unlock_irqrestore(&clock_lock, flags);
+
+        return ret;
+}
+EXPORT_SYMBOL(clk_set_rate);
+
+unsigned long clk_get_rate(struct clk *c)
+{
+        unsigned long flags;
+        unsigned long ret;
+
+        spin_lock_irqsave(&clock_lock, flags);
+
+        pr_debug("%s: %s\n", __func__, c->name);
+
+        ret = c->rate;
+
+        spin_unlock_irqrestore(&clock_lock, flags);
+        return ret;
+}
+EXPORT_SYMBOL(clk_get_rate);
+
+static int tegra_clk_init_one_from_table(struct tegra_clk_init_table *table)
+{
+        struct clk *c;
+        struct clk *p;
+
+        int ret = 0;
+
+        c = tegra_get_clock_by_name(table->name);
+
+        if (!c) {
+                pr_warning("Unable to initialize clock %s\n",
+                        table->name);
+                return -ENODEV;
+        }
+
+        if (table->parent) {
+                p = tegra_get_clock_by_name(table->parent);
+                if (!p) {
+                        pr_warning("Unable to find parent %s of clock %s\n",
+                                table->parent, table->name);
+                        return -ENODEV;
+                }
+
+                if (c->parent != p) {
+                        ret = clk_set_parent(c, p);
+                        if (ret) {
+                                pr_warning("Unable to set parent %s of clock %s: %d\n",
+                                        table->parent, table->name, ret);
+                                return -EINVAL;
+                        }
+                }
+        }
+
+        if (table->rate && table->rate != clk_get_rate(c)) {
+                ret = clk_set_rate(c, table->rate);
+                if (ret) {
+                        pr_warning("Unable to set clock %s to rate %lu: %d\n",
+                                table->name, table->rate, ret);
+                        return -EINVAL;
+                }
+        }
+
+        if (table->enabled) {
+                ret = clk_enable(c);
+                if (ret) {
+                        pr_warning("Unable to enable clock %s: %d\n",
+                                table->name, ret);
+                        return -EINVAL;
+                }
+        }
+
+        return 0;
+}
+
+void tegra_clk_init_from_table(struct tegra_clk_init_table *table)
+{
+        for (; table->name; table++)
+                tegra_clk_init_one_from_table(table);
+}
+EXPORT_SYMBOL(tegra_clk_init_from_table);
+
+void tegra_periph_reset_deassert(struct clk *c)
+{
+        tegra2_periph_reset_deassert(c);
+}
+EXPORT_SYMBOL(tegra_periph_reset_deassert);
+
+void tegra_periph_reset_assert(struct clk *c)
+{
+        tegra2_periph_reset_assert(c);
+}
+EXPORT_SYMBOL(tegra_periph_reset_assert);
+
+int __init tegra_init_clock(void)
+{
+        tegra2_init_clocks();
+
+        return 0;
+}
+
+#ifdef CONFIG_DEBUG_FS
+static struct dentry *clk_debugfs_root;
+
+
+static void clock_tree_show_one(struct seq_file *s, struct clk *c, int level)
+{
+        struct clk *child;
+        struct clk *safe;
+        const char *state = "uninit";
+        char div[5] = {0};
+
+        if (c->state == ON)
+                state = "on";
+        else if (c->state == OFF)
+                state = "off";
+
+        if (c->mul != 0 && c->div != 0) {
+                BUG_ON(c->mul > 2);
+                if (c->mul > c->div)
+                        snprintf(div, sizeof(div), "x%d", c->mul / c->div);
+                else
+                        snprintf(div, sizeof(div), "%d%s", c->div / c->mul,
+                                (c->div % c->mul) ? ".5" : "");
+        }
+
+        seq_printf(s, "%*s%-*s %-6s %-3d %-5s %-10lu\n",
+                level * 3 + 1, c->set ? "" : "*",
+                30 - level * 3, c->name,
+                state, c->refcnt, div, c->rate);
+        list_for_each_entry_safe(child, safe, &c->children, sibling) {
+                clock_tree_show_one(s, child, level + 1);
+        }
+}
+
+static int clock_tree_show(struct seq_file *s, void *data)
+{
+        struct clk *c;
+        unsigned long flags;
+        seq_printf(s, " clock                          state  ref div   rate      \n");
+        seq_printf(s, "-----------------------------------------------------------\n");
+        spin_lock_irqsave(&clock_lock, flags);
+        list_for_each_entry(c, &clocks, node)
+                if (c->parent == NULL)
+                        clock_tree_show_one(s, c, 0);
+        spin_unlock_irqrestore(&clock_lock, flags);
+        return 0;
+}
+
+static int clock_tree_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, clock_tree_show, inode->i_private);
+}
+
+static const struct file_operations clock_tree_fops = {
+        .open           = clock_tree_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+static int possible_parents_show(struct seq_file *s, void *data)
+{
+        struct clk *c = s->private;
+        int i;
+
+        for (i = 0; c->inputs[i].input; i++) {
+                char *first = (i == 0) ? "" : " ";
+                seq_printf(s, "%s%s", first, c->inputs[i].input->name);
+        }
+        seq_printf(s, "\n");
+        return 0;
+}
+
+static int possible_parents_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, possible_parents_show, inode->i_private);
+}
+
+static const struct file_operations possible_parents_fops = {
+        .open           = possible_parents_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+static int clk_debugfs_register_one(struct clk *c)
+{
+        struct dentry *d, *child, *child_tmp;
+
+        d = debugfs_create_dir(c->name, clk_debugfs_root);
+        if (!d)
+                return -ENOMEM;
+        c->dent = d;
+
+        d = debugfs_create_u8("refcnt", S_IRUGO, c->dent, (u8 *)&c->refcnt);
+        if (!d)
+                goto err_out;
+
+        d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
+        if (!d)
+                goto err_out;
+
+        d = debugfs_create_x32("flags", S_IRUGO, c->dent, (u32 *)&c->flags);
+        if (!d)
+                goto err_out;
+
+        if (c->inputs) {
+                d = debugfs_create_file("possible_parents", S_IRUGO, c->dent,
+                        c, &possible_parents_fops);
+                if (!d)
+                        goto err_out;
+        }
+
+        return 0;
+
+err_out:
+        d = c->dent;
+        list_for_each_entry_safe(child, child_tmp, &d->d_subdirs, d_u.d_child)
+                debugfs_remove(child);
+        debugfs_remove(c->dent);
+        return -ENOMEM;
+}
+
+static int clk_debugfs_register(struct clk *c)
+{
+        int err;
+        struct clk *pa = c->parent;
+
+        if (pa && !pa->dent) {
+                err = clk_debugfs_register(pa);
+                if (err)
+                        return err;
+        }
+
+        if (!c->dent) {
+                err = clk_debugfs_register_one(c);
+                if (err)
+                        return err;
+        }
+        return 0;
+}
+
+static int __init clk_debugfs_init(void)
+{
+        struct clk *c;
+        struct dentry *d;
+        int err = -ENOMEM;
+
+        d = debugfs_create_dir("clock", NULL);
+        if (!d)
+                return -ENOMEM;
+        clk_debugfs_root = d;
+
+        d = debugfs_create_file("clock_tree", S_IRUGO, clk_debugfs_root, NULL,
+                &clock_tree_fops);
+        if (!d)
+                goto err_out;
+
+        list_for_each_entry(c, &clocks, node) {
+                err = clk_debugfs_register(c);
+                if (err)
+                        goto err_out;
+        }
+        return 0;
+err_out:
+        debugfs_remove_recursive(clk_debugfs_root);
+        return err;
+}
+
+late_initcall(clk_debugfs_init);
+#endif