Merge patch series "Add OPP_LOW support for J7200"

Aniket Limaye <a-limaye@ti.com> 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/20241119003617.1871183-1-a-limaye@ti.com

include/k3-avs.h

@@ -20,11 +20,13 @@
 
 #define NUM_OPPS		4
 
+#define AM6_OPP_LOW		0
 #define AM6_OPP_NOM		1
 #define AM6_OPP_OD		2
 #define AM6_OPP_TURBO		3
 
 int k3_avs_set_opp(struct udevice *dev, int vdd_id, int opp_id);
 int k3_avs_notify_freq(int dev_id, int clk_id, u32 freq);
+int k3_avs_check_opp(struct udevice *dev, int vdd_id, int opp_id);
 
 #endif