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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * Copyright (C) 2020 Sean Anderson <seanga2@gmail.com>
- */
- #define LOG_CATEGORY UCLASS_CLK
- #include <common.h>
- #include <clk.h>
- #include <clk-uclass.h>
- #include <dm.h>
- #include <log.h>
- #include <kendryte/bypass.h>
- #include <linux/clk-provider.h>
- #include <linux/err.h>
- #define CLK_K210_BYPASS "k210_clk_bypass"
- /*
- * This is a small driver to do a software bypass of a clock if hardware bypass
- * is not working. I have tried to write this in a generic fashion, so that it
- * could be potentially broken out of the kendryte code at some future date.
- *
- * Say you have the following clock configuration
- *
- * +---+ +---+
- * |osc| |pll|
- * +---+ +---+
- * ^
- * /|
- * / |
- * / |
- * / |
- * / |
- * +---+ +---+
- * |clk| |clk|
- * +---+ +---+
- *
- * But the pll does not have a bypass, so when you configure the pll, the
- * configuration needs to change to look like
- *
- * +---+ +---+
- * |osc| |pll|
- * +---+ +---+
- * ^
- * |\
- * | \
- * | \
- * | \
- * | \
- * +---+ +---+
- * |clk| |clk|
- * +---+ +---+
- *
- * To set this up, create a bypass clock with bypassee=pll and alt=osc. When
- * creating the child clocks, set their parent to the bypass clock. After
- * creating all the children, call k210_bypass_setchildren().
- */
- static int k210_bypass_dobypass(struct k210_bypass *bypass)
- {
- int ret, i;
- /*
- * If we already have saved parents, then the children are already
- * bypassed
- */
- if (bypass->child_count && bypass->saved_parents[0])
- return 0;
- for (i = 0; i < bypass->child_count; i++) {
- struct clk *child = bypass->children[i];
- struct clk *parent = clk_get_parent(child);
- if (IS_ERR(parent)) {
- for (; i; i--)
- bypass->saved_parents[i] = NULL;
- return PTR_ERR(parent);
- }
- bypass->saved_parents[i] = parent;
- }
- for (i = 0; i < bypass->child_count; i++) {
- struct clk *child = bypass->children[i];
- ret = clk_set_parent(child, bypass->alt);
- if (ret) {
- for (; i; i--)
- clk_set_parent(bypass->children[i],
- bypass->saved_parents[i]);
- for (i = 0; i < bypass->child_count; i++)
- bypass->saved_parents[i] = NULL;
- return ret;
- }
- }
- return 0;
- }
- static int k210_bypass_unbypass(struct k210_bypass *bypass)
- {
- int err, ret, i;
- if (!bypass->child_count && !bypass->saved_parents[0]) {
- log_warning("Cannot unbypass children; dobypass not called first\n");
- return 0;
- }
- ret = 0;
- for (i = 0; i < bypass->child_count; i++) {
- err = clk_set_parent(bypass->children[i],
- bypass->saved_parents[i]);
- if (err)
- ret = err;
- bypass->saved_parents[i] = NULL;
- }
- return ret;
- }
- static ulong k210_bypass_get_rate(struct clk *clk)
- {
- struct k210_bypass *bypass = to_k210_bypass(clk);
- const struct clk_ops *ops = bypass->bypassee_ops;
- if (ops->get_rate)
- return ops->get_rate(bypass->bypassee);
- else
- return clk_get_parent_rate(bypass->bypassee);
- }
- static ulong k210_bypass_set_rate(struct clk *clk, unsigned long rate)
- {
- int ret;
- struct k210_bypass *bypass = to_k210_bypass(clk);
- const struct clk_ops *ops = bypass->bypassee_ops;
- /* Don't bother bypassing if we aren't going to set the rate */
- if (!ops->set_rate)
- return k210_bypass_get_rate(clk);
- ret = k210_bypass_dobypass(bypass);
- if (ret)
- return ret;
- ret = ops->set_rate(bypass->bypassee, rate);
- if (ret < 0)
- return ret;
- return k210_bypass_unbypass(bypass);
- }
- static int k210_bypass_set_parent(struct clk *clk, struct clk *parent)
- {
- struct k210_bypass *bypass = to_k210_bypass(clk);
- const struct clk_ops *ops = bypass->bypassee_ops;
- if (ops->set_parent)
- return ops->set_parent(bypass->bypassee, parent);
- else
- return -ENOTSUPP;
- }
- /*
- * For these next two functions, do the bypassing even if there is no
- * en-/-disable function, since the bypassing itself can be observed in between
- * calls.
- */
- static int k210_bypass_enable(struct clk *clk)
- {
- int ret;
- struct k210_bypass *bypass = to_k210_bypass(clk);
- const struct clk_ops *ops = bypass->bypassee_ops;
- ret = k210_bypass_dobypass(bypass);
- if (ret)
- return ret;
- if (ops->enable)
- ret = ops->enable(bypass->bypassee);
- else
- ret = 0;
- if (ret)
- return ret;
- return k210_bypass_unbypass(bypass);
- }
- static int k210_bypass_disable(struct clk *clk)
- {
- int ret;
- struct k210_bypass *bypass = to_k210_bypass(clk);
- const struct clk_ops *ops = bypass->bypassee_ops;
- ret = k210_bypass_dobypass(bypass);
- if (ret)
- return ret;
- if (ops->disable)
- return ops->disable(bypass->bypassee);
- else
- return 0;
- }
- static const struct clk_ops k210_bypass_ops = {
- .get_rate = k210_bypass_get_rate,
- .set_rate = k210_bypass_set_rate,
- .set_parent = k210_bypass_set_parent,
- .enable = k210_bypass_enable,
- .disable = k210_bypass_disable,
- };
- int k210_bypass_set_children(struct clk *clk, struct clk **children,
- size_t child_count)
- {
- struct k210_bypass *bypass = to_k210_bypass(clk);
- kfree(bypass->saved_parents);
- if (child_count) {
- bypass->saved_parents =
- kcalloc(child_count, sizeof(struct clk *), GFP_KERNEL);
- if (!bypass->saved_parents)
- return -ENOMEM;
- }
- bypass->child_count = child_count;
- bypass->children = children;
- return 0;
- }
- struct clk *k210_register_bypass_struct(const char *name,
- const char *parent_name,
- struct k210_bypass *bypass)
- {
- int ret;
- struct clk *clk;
- clk = &bypass->clk;
- ret = clk_register(clk, CLK_K210_BYPASS, name, parent_name);
- if (ret)
- return ERR_PTR(ret);
- bypass->bypassee->dev = clk->dev;
- return clk;
- }
- struct clk *k210_register_bypass(const char *name, const char *parent_name,
- struct clk *bypassee,
- const struct clk_ops *bypassee_ops,
- struct clk *alt)
- {
- struct clk *clk;
- struct k210_bypass *bypass;
- bypass = kzalloc(sizeof(*bypass), GFP_KERNEL);
- if (!bypass)
- return ERR_PTR(-ENOMEM);
- bypass->bypassee = bypassee;
- bypass->bypassee_ops = bypassee_ops;
- bypass->alt = alt;
- clk = k210_register_bypass_struct(name, parent_name, bypass);
- if (IS_ERR(clk))
- kfree(bypass);
- return clk;
- }
- U_BOOT_DRIVER(k210_bypass) = {
- .name = CLK_K210_BYPASS,
- .id = UCLASS_CLK,
- .ops = &k210_bypass_ops,
- };
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