Support regulators coupling on NVIDIA Tegra20/30

There is voltage coupling between three regulators on Tegra20 boards and between two on Tegra30. The voltage coupling is a SoC-level feature and thus it is mandatory and common for all of the Tegra boards.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 .../nvidia,tegra-regulators-coupling.txt      | 65 +++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/nvidia,tegra-regulators-coupling.txt

Documentation/devicetree/bindings/regulator/nvidia,tegra-regulators-coupling.txt new file +55 -0

new file mode 100644
index 000000000000..4bf2dbf7c6cc
@@ -0,0 +1,65 @@
+NVIDIA Tegra Regulators Coupling
+================================
+
+NVIDIA Tegra SoC's have a mandatory voltage-coupling between regulators.
+Thus on Tegra20 there are 3 coupled regulators and on NVIDIA Tegra30
+there are 2.
+
+Tegra20 voltage coupling
+------------------------
+
+On Tegra20 SoC's there are 3 coupled regulators: CORE, RTC and CPU.
+The CORE and RTC voltages shall be in a range of 170mV from each other
+and they both shall be higher than the CPU voltage by at least 120mV.
+
+Tegra30 voltage coupling
+------------------------
+
+On Tegra30 SoC's there are 2 coupled regulators: CORE and CPU. The CORE
+and CPU voltages shall be in a range of 300mV from each other and CORE
+voltage shall be higher than the CPU by N mV, where N depends on the CPU
+voltage.
+
+Required properties:
+- nvidia,tegra-core-regulator: Boolean property that designates regulator
+  as the "Core domain" voltage regulator.
+- nvidia,tegra-rtc-regulator: Boolean property that designates regulator
+  as the "RTC domain" voltage regulator.
+- nvidia,tegra-cpu-regulator: Boolean property that designates regulator
+  as the "CPU domain" voltage regulator.
+
+Example:
+
+	pmic {
+		regulators {
+			core_vdd_reg: core {
+				regulator-name = "vdd_core";
+				regulator-min-microvolt = <950000>;
+				regulator-max-microvolt = <1300000>;
+				regulator-coupled-with = <&rtc_vdd_reg &cpu_vdd_reg>;
+				regulator-coupled-max-spread = <170000 550000>;
+
+				nvidia,tegra-core-regulator;
+			};
+
+			rtc_vdd_reg: rtc {
+				regulator-name = "vdd_rtc";
+				regulator-min-microvolt = <950000>;
+				regulator-max-microvolt = <1300000>;
+				regulator-coupled-with = <&core_vdd_reg &cpu_vdd_reg>;
+				regulator-coupled-max-spread = <170000 550000>;
+
+				nvidia,tegra-rtc-regulator;
+			};
+
+			cpu_vdd_reg: cpu {

There is voltage coupling between three regulators on Tegra20 boards and between two on Tegra30. The voltage coupling is a SoC-level feature and thus it is mandatory and common for all of the Tegra boards.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 .../nvidia,tegra-regulators-coupling.txt      | 65 +++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/nvidia,tegra-regulators-coupling.txt

Add regulators coupler for Tegra30 SoCs that performs voltage balancing of a coupled regulators and thus provides voltage scaling functionality.

There are 2 coupled regulators on all Tegra30 SoCs: CORE and CPU. The coupled regulator voltages shall be in a range of 300mV from each other and CORE voltage shall be higher than the CPU by N mV, where N depends on the CPU voltage.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/soc/tegra/Kconfig              |   4 +
 drivers/soc/tegra/Makefile             |   1 +
 drivers/soc/tegra/regulators-tegra30.c | 316 +++++++++++++++++++++++++
 3 files changed, 321 insertions(+)
 create mode 100644 drivers/soc/tegra/regulators-tegra30.c

drivers/soc/tegra/regulators-tegra30.c new file +8 -0

+
+static int tegra30_core_cpu_limit(int cpu_uV)
+{
+	if (cpu_uV < 800000)
+		return 950000;
+
+	if (cpu_uV < 900000)
+		return 1000000;

Quoted 16 lines

Add regulators coupler for Tegra30 SoCs that performs voltage balancing of a coupled regulators and thus provides voltage scaling functionality.

There are 2 coupled regulators on all Tegra30 SoCs: CORE and CPU. The coupled regulator voltages shall be in a range of 300mV from each other and CORE voltage shall be higher than the CPU by N mV, where N depends on the CPU voltage.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/soc/tegra/Kconfig              |   4 +
 drivers/soc/tegra/Makefile             |   1 +
 drivers/soc/tegra/regulators-tegra30.c | 316 +++++++++++++++++++++++++
 3 files changed, 321 insertions(+)
 create mode 100644 drivers/soc/tegra/regulators-tegra30.c

...

Quoted 11 lines

drivers/soc/tegra/regulators-tegra30.c new file +11 -0

+
+static int tegra30_core_cpu_limit(int cpu_uV)
+{
+	if (cpu_uV < 800000)
+		return 950000;
+
+	if (cpu_uV < 900000)
+		return 1000000;
+
+	if (cpu_uV < 1000000)
+		return 1100000;

drivers/soc/tegra/regulators-tegra30.c line 82

Quoted 7 lines

drivers/soc/tegra/regulators-tegra30.c new file +7 -0

+
+	if (cpu_uV < 1100000)
+		return 1200000;
+
+	if (cpu_uV < 1250000) {
+		switch (tegra_sku_info.cpu_speedo_id) {
+		case 0 ... 1:

Aren't we supposed to add /* fall through */ here now?

drivers/soc/tegra/regulators-tegra30.c line 91

Quoted 9 lines

drivers/soc/tegra/regulators-tegra30.c new file +9 -0

+		case 4:
+		case 7 ... 8:
+			return 1200000;
+
+		default:
+			return 1300000;
+		}
+	}
+

Other than that, this looks ok to me.

02.08.2019 17:05, Peter De Schrijver пишет:

Quoted 30 lines · Dmitry Osipenko

Quoted 16 lines

Add regulators coupler for Tegra30 SoCs that performs voltage balancing of a coupled regulators and thus provides voltage scaling functionality.

There are 2 coupled regulators on all Tegra30 SoCs: CORE and CPU. The coupled regulator voltages shall be in a range of 300mV from each other and CORE voltage shall be higher than the CPU by N mV, where N depends on the CPU voltage.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/soc/tegra/Kconfig              |   4 +
 drivers/soc/tegra/Makefile             |   1 +
 drivers/soc/tegra/regulators-tegra30.c | 316 +++++++++++++++++++++++++
 3 files changed, 321 insertions(+)
 create mode 100644 drivers/soc/tegra/regulators-tegra30.c

...

Quoted 11 lines

drivers/soc/tegra/regulators-tegra30.c new file +11 -0

+
+static int tegra30_core_cpu_limit(int cpu_uV)
+{
+	if (cpu_uV < 800000)
+		return 950000;
+
+	if (cpu_uV < 900000)
+		return 1000000;
+
+	if (cpu_uV < 1000000)
+		return 1100000;

Quoted 8 lines

drivers/soc/tegra/regulators-tegra30.c line 82

Quoted 7 lines

drivers/soc/tegra/regulators-tegra30.c new file +7 -0

+
+	if (cpu_uV < 1100000)
+		return 1200000;
+
+	if (cpu_uV < 1250000) {
+		switch (tegra_sku_info.cpu_speedo_id) {
+		case 0 ... 1:

Aren't we supposed to add /* fall through */ here now?

There is no compiler warning if there is nothing in-between of the case-switches, so annotation isn't really necessary here. Of course it is possible to add an explicit annotation just to make clear the fall-through intention.

Quoted 11 lines

drivers/soc/tegra/regulators-tegra30.c line 91

Quoted 9 lines

drivers/soc/tegra/regulators-tegra30.c new file +9 -0

+		case 4:
+		case 7 ... 8:
+			return 1200000;
+
+		default:
+			return 1300000;
+		}
+	}
+

Other than that, this looks ok to me.

Awesome, thank you very much! Explicit ACK will be appreciated as well.

Quoted 40 lines

02.08.2019 17:05, Peter De Schrijver пишет:

Quoted 38 lines · Dmitry Osipenko

Quoted 16 lines

Add regulators coupler for Tegra30 SoCs that performs voltage balancing of a coupled regulators and thus provides voltage scaling functionality.

There are 2 coupled regulators on all Tegra30 SoCs: CORE and CPU. The coupled regulator voltages shall be in a range of 300mV from each other and CORE voltage shall be higher than the CPU by N mV, where N depends on the CPU voltage.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/soc/tegra/Kconfig              |   4 +
 drivers/soc/tegra/Makefile             |   1 +
 drivers/soc/tegra/regulators-tegra30.c | 316 +++++++++++++++++++++++++
 3 files changed, 321 insertions(+)
 create mode 100644 drivers/soc/tegra/regulators-tegra30.c

...

Quoted 8 lines

drivers/soc/tegra/regulators-tegra30.c new file +8 -0

+
+static int tegra30_core_cpu_limit(int cpu_uV)
+{
+	if (cpu_uV < 800000)
+		return 950000;
+
+	if (cpu_uV < 900000)
+		return 1000000;

drivers/soc/tegra/regulators-tegra30.c line 82

Quoted 10 lines

drivers/soc/tegra/regulators-tegra30.c new file +10 -0

+
+	if (cpu_uV < 1000000)
+		return 1100000;
+
+	if (cpu_uV < 1100000)
+		return 1200000;
+
+	if (cpu_uV < 1250000) {
+		switch (tegra_sku_info.cpu_speedo_id) {
+		case 0 ... 1:

Aren't we supposed to add /* fall through */ here now?

Quoted 5 lines

There is no compiler warning if there is nothing in-between of the case-switches, so annotation isn't really necessary here. Of course it is possible to add an explicit annotation just to make clear the fall-through intention.

Ah. Ok. Whatever you want then :)

Quoted 12 lines

Quoted 11 lines

drivers/soc/tegra/regulators-tegra30.c line 91

Quoted 9 lines

drivers/soc/tegra/regulators-tegra30.c new file +9 -0

+		case 4:
+		case 7 ... 8:
+			return 1200000;
+
+		default:
+			return 1300000;
+		}
+	}
+

Other than that, this looks ok to me.

Quoted 1 line

Awesome, thank you very much! Explicit ACK will be appreciated as well.

Acked-by Peter De Schrijver <[email protected]>

05.08.2019 11:33, Peter De Schrijver пишет:

Quoted 47 lines · Dmitry Osipenko

Quoted 45 lines

02.08.2019 17:05, Peter De Schrijver пишет:

Quoted 30 lines · Dmitry Osipenko

Quoted 16 lines

Add regulators coupler for Tegra30 SoCs that performs voltage balancing of a coupled regulators and thus provides voltage scaling functionality.

There are 2 coupled regulators on all Tegra30 SoCs: CORE and CPU. The coupled regulator voltages shall be in a range of 300mV from each other and CORE voltage shall be higher than the CPU by N mV, where N depends on the CPU voltage.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/soc/tegra/Kconfig              |   4 +
 drivers/soc/tegra/Makefile             |   1 +
 drivers/soc/tegra/regulators-tegra30.c | 316 +++++++++++++++++++++++++
 3 files changed, 321 insertions(+)
 create mode 100644 drivers/soc/tegra/regulators-tegra30.c

...

Quoted 11 lines

drivers/soc/tegra/regulators-tegra30.c new file +11 -0

+
+static int tegra30_core_cpu_limit(int cpu_uV)
+{
+	if (cpu_uV < 800000)
+		return 950000;
+
+	if (cpu_uV < 900000)
+		return 1000000;
+
+	if (cpu_uV < 1000000)
+		return 1100000;

Quoted 8 lines

drivers/soc/tegra/regulators-tegra30.c line 82

Quoted 7 lines

drivers/soc/tegra/regulators-tegra30.c new file +7 -0

+
+	if (cpu_uV < 1100000)
+		return 1200000;
+
+	if (cpu_uV < 1250000) {
+		switch (tegra_sku_info.cpu_speedo_id) {
+		case 0 ... 1:

Aren't we supposed to add /* fall through */ here now?

There is no compiler warning if there is nothing in-between of the case-switches, so annotation isn't really necessary here. Of course it is possible to add an explicit annotation just to make clear the fall-through intention.

Quoted 1 line

Ah. Ok. Whatever you want then :)

I'll add the comments if there will be a need to re-spin this series.

Quoted 15 lines

Quoted 12 lines

Quoted 11 lines

drivers/soc/tegra/regulators-tegra30.c line 91

Quoted 9 lines

drivers/soc/tegra/regulators-tegra30.c new file +9 -0

+		case 4:
+		case 7 ... 8:
+			return 1200000;
+
+		default:
+			return 1300000;
+		}
+	}
+

Other than that, this looks ok to me.

Quoted 1 line

Awesome, thank you very much! Explicit ACK will be appreciated as well.

Acked-by Peter De Schrijver <[email protected]>

Hello,

The voltage regulators need to be coupled on NVIDIA Tegra20 and Tegra30 SoCs in order to provide voltage scaling functionality in a generic way. All necessary regulator-core patches that added support for the regulators coupling are already have been merge into mainline kernel. This series adds customized voltage couplers for Tegra20/30 SoCs, paving the way for a refined CPUFreq driver that will utilize voltage scaling and other neat features. This is a resend of a leftover patches from a previous series
[1] that was partially applied by Mark Brown. Please review, thanks in advance!

[1] https://patchwork.ozlabs.org/project/linux-tegra/list/?series=115626

Changelog:

v2: - Some days ago OPP framework got a change that makes CPU regulator
to be enabled at the time of CPUFreq's driver initializing OPPs. In a result the CPU's voltage is dropped to a minimum value on CPUFreq's setting up because there are no consumers at the time of regulator's enabling, thus CPU is getting into a big trouble. This problem is now resolved in the couplers code by assuming that min_uV=current_uV for CPU's regulator if it doesn't have any active consumers.

Dmitry Osipenko (3):
dt-bindings: regulator: Document regulators coupling of NVIDIA

    Tegra20/30 SoCs

soc/tegra: regulators: Add regulators coupler for Tegra20 soc/tegra: regulators: Add regulators coupler for Tegra30