From: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
Allow for a per clock custom selection of clocks in the device tree.
Basic setup in dt looks like this:
clock@BCM2835_CLOCK_PCM {
reg = <BCM2835_CLOCK_PCM>;
parent-clock-names = "xosc", "plld_per", "plla_per", "pll_aux_per";
};
Special care had to be taken when only a single clock is assigned,
as then set_parent_rate is not called - so the register has to get
set up immediately.
To allow for custom order of the clocks (giving preference)
an additional mapping between IDs is required when handling
get/set parent.
The default parent clocks are assumed to be all available clocks
against which the "selected" parents are checked.
Signed-off-by: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
---
drivers/clk/bcm/clk-bcm2835.c | 124 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 119 insertions(+), 5 deletions(-)
diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 1c714d0..8fccbd3 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -702,6 +702,7 @@ struct bcm2835_clock_data {
const char *const *parents;
int num_mux_parents;
+ u8 *parents_idx;
u32 ctl_reg;
u32 div_reg;
@@ -1706,15 +1707,30 @@ static int bcm2835_clock_determine_rate(struct clk_hw *hw,
return 0;
}
+static int _bcm2835_clk_set_parent(struct bcm2835_cprman *cprman,
+ const struct bcm2835_clock_data *data,
+ u8 index)
+{
+ u8 src;
+
+ /* map the index if we got a map */
+ if (data->parents_idx)
+ index = data->parents_idx[index];
+
+ /* calc the source */
+ src = (index << CM_SRC_SHIFT) & CM_SRC_MASK;
+
+ cprman_write(cprman, data->ctl_reg, src);
+ return 0;
+}
+
static int bcm2835_clock_set_parent(struct clk_hw *hw, u8 index)
{
struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
struct bcm2835_cprman *cprman = clock->cprman;
const struct bcm2835_clock_data *data = clock->data;
- u8 src = (index << CM_SRC_SHIFT) & CM_SRC_MASK;
- cprman_write(cprman, data->ctl_reg, src);
- return 0;
+ return _bcm2835_clk_set_parent(cprman, data, index);
}
static u8 bcm2835_clock_get_parent(struct clk_hw *hw)
@@ -1723,10 +1739,23 @@ static u8 bcm2835_clock_get_parent(struct clk_hw *hw)
struct bcm2835_cprman *cprman = clock->cprman;
const struct bcm2835_clock_data *data = clock->data;
u32 src = cprman_read(cprman, data->ctl_reg);
+ int i;
- return (src & CM_SRC_MASK) >> CM_SRC_SHIFT;
-}
+ /* translate src to default index */
+ src = (src & CM_SRC_MASK) >> CM_SRC_SHIFT;
+
+ /* without overrides overrides return the value */
+ if (!data->parents_idx)
+ return src;
+ /* otherwise iterate over fields to find it */
+ for (i = 0; i < data->num_mux_parents ; i++)
+ if (data->parents_idx[i] == src)
+ return i;
+
+ /* if not found */
+ return -EINVAL;
+}
static const struct clk_ops bcm2835_clock_clk_ops = {
.is_prepared = bcm2835_clock_is_on,
@@ -1874,6 +1903,88 @@ bcm2835_register_pll_divider(struct bcm2835_cprman *cprman,
return clk;
}
+static void bcm2835_register_clock_of_parents(
+ struct bcm2835_cprman *cprman,
+ struct bcm2835_clock_data *data,
+ struct device_node *nc)
+{
+ struct device *dev = cprman->dev;
+ u8 *parents_idx;
+ const char **parents;
+ const char *name;
+ int err, names, i, j;
+
+ /* check number of strings */
+ names = of_property_count_strings(nc, "parent-clock-names");
+ if (names < 0)
+ return;
+ if (names > data->num_mux_parents) {
+ dev_err(dev,
+ "%s: dt-property parent-clock-names has more entries (%d) than available parent clocks (%d)\n",
+ of_node_full_name(nc), names, data->num_mux_parents);
+ return;
+ }
+
+ /* allocate parents */
+ parents = devm_kzalloc(dev, sizeof(*parents) * names, GFP_KERNEL);
+ if (!parents)
+ return;
+
+ /* allocate parents index */
+ parents_idx = devm_kzalloc(dev, sizeof(*parents_idx) * names,
+ GFP_KERNEL);
+ if (!parents_idx) {
+ devm_kfree(dev, parents);
+ return;
+ }
+
+ /* and check the parents against list of allowed parents */
+ for (i = 0; i < names; i++) {
+ /* get the string */
+ err = of_property_read_string_index(nc, "parent-clock-names",
+ i, &name);
+ if (err) {
+ devm_kfree(dev, parents_idx);
+ devm_kfree(dev, parents);
+ dev_err(dev,
+ "%s: could not get parent-clock-names[%d] - %d\n",
+ of_node_full_name(nc), i, err);
+ return;
+ }
+ /* check against available parents - the default list */
+ for (j = 0; j < data->num_mux_parents; j++) {
+ if (strcmp(data->parents[j], name) == 0) {
+ parents[i] = data->parents[j];
+ parents_idx[i] = j;
+ break;
+ }
+ }
+ /* if there was no match */
+ if (!parents[i]) {
+ devm_kfree(dev, parents_idx);
+ devm_kfree(dev, parents);
+ dev_err(dev,
+ "%s: could not find %s in list of allowed parent clocks\n",
+ of_node_full_name(nc), name);
+ return;
+ }
+ }
+
+ /* finally assign it */
+ data->num_mux_parents = names;
+ data->parents = parents;
+ data->parents_idx = parents_idx;
+
+ /*
+ * if there is only one parent, then use that one immediately,
+ * as with only one parent clock_set_parent does not get called
+ * and it is assumed that everything is set up, so
+ * we need to do that before anything else...
+ */
+ if (names == 1)
+ _bcm2835_clk_set_parent(cprman, data, 0);
+}
+
static const struct bcm2835_clock_data *bcm2835_register_clock_of(
struct bcm2835_cprman *cprman,
const struct bcm2835_clock_data *data_orig,
@@ -1894,6 +2005,9 @@ static const struct bcm2835_clock_data *bcm2835_register_clock_of(
return data_orig;
memcpy(data, data_orig, sizeof(*data));
+ /* apply overrides */
+ bcm2835_register_clock_of_parents(cprman, data, nc);
+
/* and return the result */
return data;
}
--
1.7.10.4
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