[PATCH v1 20/30] usb: chipidea: tegra: Support OPP and SoC core voltage scaling

Dmitry Osipenko
2020-11-04T23:47:22Z

Add initial OPP and SoC CORE voltage scaling support to the Tegra UDC
driver. This is required for enabling system-wide DVFS on older Tegra
SoCs.

Tested-by: Peter Geis <pgwipeout@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
drivers/usb/chipidea/Kconfig | 1 +
drivers/usb/chipidea/ci_hdrc_tegra.c | 79 ++++++++++++++++++++++++++++
2 files changed, 80 insertions(+)

diff --git a/drivers/usb/chipidea/Kconfig b/drivers/usb/chipidea/Kconfig
index 8bafcfc6080d..6a5bc08711d6 100644
--- a/drivers/usb/chipidea/Kconfig
+++ b/drivers/usb/chipidea/Kconfig
@@ -56,6 +56,7 @@ config USB_CHIPIDEA_TEGRA
tristate "Enable Tegra UDC glue driver" if EMBEDDED
depends on OF
depends on USB_CHIPIDEA_UDC
+ select PM_OPP
default USB_CHIPIDEA

endif
diff --git a/drivers/usb/chipidea/ci_hdrc_tegra.c b/drivers/usb/chipidea/ci_hdrc_tegra.c
index 7455df0ede49..7f0403e810fe 100644
--- a/drivers/usb/chipidea/ci_hdrc_tegra.c
+++ b/drivers/usb/chipidea/ci_hdrc_tegra.c
@@ -6,6 +6,7 @@
#include <linux/clk.h>
#include <linux/module.h>
#include <linux/of_device.h>
+#include <linux/pm_opp.h>
#include <linux/reset.h>

#include <linux/usb/chipidea.h>
@@ -47,6 +48,79 @@ static const struct of_device_id tegra_udc_of_match[] = {
};
MODULE_DEVICE_TABLE(of, tegra_udc_of_match);

+static void tegra_udc_deinit_opp_table(void *data)
+{
+ struct device *dev = data;
+ struct opp_table *opp_table;
+
+ opp_table = dev_pm_opp_get_opp_table(dev);
+ dev_pm_opp_of_remove_table(dev);
+ dev_pm_opp_put_regulators(opp_table);
+ dev_pm_opp_put_opp_table(opp_table);
+}
+
+static int devm_tegra_udc_init_opp_table(struct device *dev)
+{
+ unsigned long rate = ULONG_MAX;
+ struct opp_table *opp_table;
+ const char *rname = "core";
+ struct dev_pm_opp *opp;
+ int err;
+
+ /* legacy device-trees don't have OPP table */
+ if (!device_property_present(dev, "operating-points-v2"))
+ return 0;
+
+ /* voltage scaling is optional */
+ if (device_property_present(dev, "core-supply"))
+ opp_table = dev_pm_opp_set_regulators(dev, &rname, 1);
+ else
+ opp_table = dev_pm_opp_get_opp_table(dev);
+
+ if (IS_ERR(opp_table))
+ return dev_err_probe(dev, PTR_ERR(opp_table),
+ "failed to prepare OPP table\n");
+
+ err = dev_pm_opp_of_add_table(dev);
+ if (err) {
+ dev_err(dev, "failed to add OPP table: %d\n", err);
+ goto put_table;
+ }
+
+ /* find suitable OPP for the maximum clock rate */
+ opp = dev_pm_opp_find_freq_floor(dev, &rate);
+ err = PTR_ERR_OR_ZERO(opp);
+ if (err) {
+ dev_err(dev, "failed to get OPP: %d\n", err);
+ goto remove_table;
+ }
+
+ dev_pm_opp_put(opp);
+
+ /*
+ * First dummy rate-set initializes voltage vote by setting voltage
+ * in accordance to the clock rate.
+ */
+ err = dev_pm_opp_set_rate(dev, rate);
+ if (err) {
+ dev_err(dev, "failed to initialize OPP clock: %d\n", err);
+ goto remove_table;
+ }
+
+ err = devm_add_action(dev, tegra_udc_deinit_opp_table, dev);
+ if (err)
+ goto remove_table;
+
+ return 0;
+
+remove_table:
+ dev_pm_opp_of_remove_table(dev);
+put_table:
+ dev_pm_opp_put_regulators(opp_table);
+
+ return err;
+}
+
static int tegra_udc_probe(struct platform_device *pdev)
{
const struct tegra_udc_soc_info *soc;
@@ -77,6 +151,11 @@ static int tegra_udc_probe(struct platform_device *pdev)
return err;
}

+ err = devm_tegra_udc_init_opp_table(&pdev->dev);
+ if (err)
+ return dev_err_probe(&pdev->dev, err,
+ "failed to initialize OPP\n");
+
err = clk_prepare_enable(udc->clk);
if (err < 0) {
dev_err(&pdev->dev, "failed to enable clock: %d\n", err);
--
2.27.0