Re: [RFC PATCH v2 4/6] PM: opp: allow control of multiple clocks

Bjorn Andersson
2022-04-12T17:13:24Z

On Mon 11 Apr 08:43 PDT 2022, Krzysztof Kozlowski wrote:

> Devices might need to control several clocks when scaling the frequency
> and voltage. Example is the Universal Flash Storage (UFS) which scales
> several independent clocks with change of performance levels.
>
> Add parsing of multiple clocks and clock names and scale all of them,
> when needed. If only one clock is provided, the code should behave the
> same as before.
>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> ---
> drivers/opp/core.c | 205 ++++++++++++++++++++++++++++++++---------
> drivers/opp/of.c | 48 ++++++++++
> drivers/opp/opp.h | 9 +-
> include/linux/pm_opp.h | 23 +++++
> 4 files changed, 242 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
[..]
> @@ -1295,21 +1344,32 @@ static struct opp_table *_update_opp_table_clk(struct device *dev,
> * Return early if we don't need to get clk or we have already tried it
> * earlier.
> */
> - if (!getclk || IS_ERR(opp_table) || opp_table->clk)
> + if (!getclk || IS_ERR(opp_table) || opp_table->clks)
> return opp_table;
>
> + opp_table->clks = kmalloc_array(1, sizeof(*opp_table->clks),
> + GFP_KERNEL);

This seems to be 81 chars long, perhaps worth not line breaking?

> + if (!opp_table->clks)
> + return ERR_PTR(-ENOMEM);
> +
> /* Find clk for the device */
> - opp_table->clk = clk_get(dev, NULL);
> + opp_table->clks[0] = clk_get(dev, NULL);
>
> - ret = PTR_ERR_OR_ZERO(opp_table->clk);
> - if (!ret)
> + ret = PTR_ERR_OR_ZERO(opp_table->clks[0]);
> + if (!ret) {
> + opp_table->clk_count = 1;
> return opp_table;
> + }
[..]
> +struct opp_table *dev_pm_opp_set_clknames(struct device *dev,
> + const char * const names[],
> + unsigned int count)
> {
> struct opp_table *opp_table;
> - int ret;
> + struct clk *clk;
> + int ret, i;
>
> opp_table = _add_opp_table(dev, false);
> if (IS_ERR(opp_table))
> @@ -2159,70 +2259,92 @@ struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char *name)
> }
>
> /* clk shouldn't be initialized at this point */
> - if (WARN_ON(opp_table->clk)) {
> + if (WARN_ON(opp_table->clks)) {
> ret = -EBUSY;
> goto err;
> }
>
> - /* Find clk for the device */
> - opp_table->clk = clk_get(dev, name);
> - if (IS_ERR(opp_table->clk)) {
> - ret = dev_err_probe(dev, PTR_ERR(opp_table->clk),
> - "%s: Couldn't find clock\n", __func__);
> + opp_table->clks = kmalloc_array(count, sizeof(*opp_table->clks),
> + GFP_KERNEL);
> + if (!opp_table->clks) {
> + ret = -ENOMEM;
> goto err;
> }
>
> + for (i = 0; i < count; i++) {
> + clk = clk_get(dev, names[i]);
> + if (IS_ERR(clk)) {
> + ret = dev_err_probe(dev, PTR_ERR(clk),
> + "%s: Couldn't find clock %s\n",
> + __func__, names[i]);
> + goto free_clks;
> + }
> +
> + opp_table->clks[i] = clk;
> + }

Wouldn't it be convenient to make clks a struct clk_bulk_data array
and use clk_bulk_get()/clk_bulk_put() instead?

> +
> + opp_table->clk_count = count;
> +
> return opp_table;
>
> +free_clks:
> + while (i != 0)
> + clk_put(opp_table->clks[--i]);
> +
> + kfree(opp_table->clks);
> + opp_table->clks = NULL;
> + opp_table->clk_count = -1;
> err:
> dev_pm_opp_put_opp_table(opp_table);
>
> return ERR_PTR(ret);
> }
> -EXPORT_SYMBOL_GPL(dev_pm_opp_set_clkname);
> +EXPORT_SYMBOL_GPL(dev_pm_opp_set_clknames);
[..]
> +static int _read_clocks(struct dev_pm_opp *opp, struct opp_table *opp_table,
> + struct device_node *np)
> +{
> + int count, ret;
> + u64 *freq;
> +
> + count = of_property_count_u64_elems(np, "opp-hz");
> + if (count < 0) {
> + pr_err("%s: Invalid %s property (%d)\n",
> + __func__, of_node_full_name(np), count);

Wouldn't %pOF be convenient to use here, seems like it becomes short
enough that you don't have to wrap this line then.

> + return count;
> + }
> +
> + if (count != opp_table->clk_count) {
> + pr_err("%s: number of rates %d does not match number of clocks %d in %s\n",
> + __func__, count, opp_table->clk_count,
> + of_node_full_name(np));
> + return -EINVAL;
> + }
> +
> + freq = kmalloc_array(count, sizeof(*freq), GFP_KERNEL);
> + if (!freq)
> + return -ENOMEM;
> +
> + ret = of_property_read_u64_array(np, "opp-hz", freq, count);
> + if (ret) {
> + pr_err("%s: error parsing %s: %d\n", __func__,
> + of_node_full_name(np), ret);
> + ret = -EINVAL;
> + goto free_freq;
> + }

Regards,
Bjorn