Merge patch series "Add OPP_LOW support for J7200"

Aniket Limaye <[email protected]> says:

This series adds OPP_LOW spec data in k3_avs driver and enables a config
option to select the OPP_LOW performance point.

J7200 SOC supports OPP_LOW and OPP_NOM as two Operating Performance
Points as per (7.5 Operating Performance Points) section in the
Datasheet [0].
- A72SS/MSMC at 2 GHz/1GHz operation must use OPP_NOM.
- A72SS/MSMC at 1 GHz/500 MHz operation can use OPP_NOM or OPP_LOW
  voltage (though OPP_LOW voltage is recommended to reduce power
  consumption).

The actual OPP voltage for the device is read from the efuse and
updated in k3_avs_probe().

The default j7200 devicetree and k3_avs driver set OPP_NOM spec
frequency and voltage.

In the board init file, if K3_OPP_LOW config is enabled, Check if
OPP_LOW AVS voltage read from efuse is valid and update frequency (A72
and MSMC) and voltage (VDD_CPU) as per the OPP_LOW spec.

[0]: https://www.ti.com/lit/gpn/dra821u  (J7200 Datasheet)

Test logs:
https://gist.github.com/aniket-l/328ad93ed60c2419ed7be9f85e6b6075
- With series applied on master and CONFIG_K3_OPP_LOW enabled in
  j7200_evm_r5_defconfig
- Logs shown with and without efuse register programmed for OPP_0
  (Errors out if OPP_0 not found, programs OPP_LOW spec if found)
- Voltage update verified using 'i2c md 0x4c 0xe' in u-boot
- Frequency update verified using 'k3conf clock dump' in linux

Link: https://lore.kernel.org/r/[email protected]

1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/misc/k3_avs.c b/drivers/misc/k3_avs.c
index 99a18a109b7..0774e0a4c9e 100644
--- a/drivers/misc/k3_avs.c
+++ b/drivers/misc/k3_avs.c
@@ -121,6 +121,11 @@ static int k3_avs_program_voltage(struct k3_avs_privdata *priv,
 	if (!vd->supply)
 		return -ENODEV;
 
+	if (!volt) {
+		dev_err(priv->dev, "No efuse found for opp_%d\n", opp_id);
+		return -EINVAL;
+	}
+
 	vd->opp = opp_id;
 	vd->flags |= VD_FLAG_INIT_DONE;
 
@@ -193,6 +198,33 @@ static int match_opp(struct vd_data *vd, u32 freq)
 }
 
 /**
+ * k3_check_opp: Check for presence of opp efuse
+ * @dev: AVS device
+ * @vdd_id: voltage domain ID
+ * @opp_id: opp id to check if voltage is present
+ *
+ * Checks to see if an opp has voltage. k3_avs probe will populate
+ * voltage data if efuse is present. Returns 0 if data is valid.
+ */
+int k3_avs_check_opp(struct udevice *dev, int vdd_id, int opp_id)
+{
+	struct k3_avs_privdata *priv = dev_get_priv(dev);
+	struct vd_data *vd;
+	int volt;
+
+	vd = get_vd(priv, vdd_id);
+	if (!vd)
+		return -EINVAL;
+
+	volt = vd->opps[opp_id].volt;
+	if (volt)
+		return 0;
+
+	printf("No efuse found for opp_%d\n", opp_id);
+	return -EINVAL;
+}
+
+/**
  * k3_avs_notify_freq: Notify clock rate change towards AVS subsystem
  * @dev_id: Device ID for the clock to be changed
  * @clk_id: Clock ID for the clock to be changed
@@ -501,6 +533,10 @@ static struct vd_data j721e_vd_data[] = {
 		.dev_id = 202, /* J721E_DEV_A72SS0_CORE0 */
 		.clk_id = 2, /* ARM clock */
 		.opps = {
+			[AM6_OPP_LOW] = {
+				.volt = 0, /* voltage TBD after OPP fuse reading */
+				.freq = 1000000000,
+			},
 			[AM6_OPP_NOM] = {
 				.volt = 880000, /* TBD in DM */
 				.freq = 2000000000,