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Original question:

DRA829V: EPWM: Linux support of module

DRA829V: J721E: EPWM testing on J7 EVM using Linux

Awais Belal1
Intellectual 300 points
Part Number: DRA829V

Hi Experts,

Going through the J7 (DRA82x/TDA4x) SDKs I see that the SDKs do not provide support for the EPWM module on the SoC and the same was clarified in the related ticket. However, going through the TRM and other platform support I am pretty certain that the drivers

<kernel-source>/drivers/clk/keystone/syscon-clk.c
<kernel-source>/drivers/pwm/pwm-tiehrpwm.c

can be used for the J7 EVM with appropriate changes to the dts and enabling relevant kernel configurations. So the software bit can be taken care of (I think). Is my understanding correct here?

The next and more tricky question that I currently have is that whether on the EVM platform one of the EPWM [0-5] module's outputs are routed in a way that it can be tested at hardware level i.e. is there a pinout on the board where the signals from any one of these modules (EPWM0/5) can be measured? The schematic is pretty complex in a way that one has to chase a pin going from SoM board to the CP board, is there an easier way for identifying this?

  • 0
    TI__Mastermind 47700 points

    Are you using the MIPI-60 emulation interface (J16) for testing you code?  If not, several of the EPWM signals are muxed on the TRC signals and are available on this connector.  The EVM is shipped with 2 different MIPI-60 adapters which have pin headers.  This should make probing the signals easier than probing the fine-pitch MIPI-60 connector.  Make sure the EVM is configured to access the MIPI-60 interface by configuring dip switch SW3 bit 2 to ON.

    One example of pin mux is TRC_DATA1 is mux'ed with EHRPWM0_A

    If you have the Gateway/Ethernet Switch Expansion board available - it has several headers which provide access to EPWMs as well.

  • 0 in reply to Robert Eschler
    Intellectual 300 points

    Hi Robert,

    Thanks a lot for the response. I was hoping to see a signal on the MIPI-60 connector as you've suggested. I applied a patch on the dts hoping that my understanding of the platform was correct. However, I see an EL3 exception when Linux boots :(

    Patch

    From 0f0d4a233d643d441cf07a301559962368702841 Mon Sep 17 00:00:00 2001
From: Awais Belal <awais_belal@mentor.com>
Date: Thu, 11 Feb 2021 19:53:39 +0500
Subject: [PATCH] k3-j721e-main.dtsi: populate ehrpwm nodes

The IP block for the EPWM module is identical to what we
have on an AM654x so the same definitions/drivers can be
used with appropriate adjustments to clocks and power
domains.

Signed-off-by: Awais Belal <awais_belal@mentor.com>
---
 arch/arm64/boot/dts/ti/k3-j721e-main.dtsi | 60 +++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
index 4e04d5b14..85a364c51 100644
--- a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
@@ -65,6 +65,12 @@
 			mux-reg-masks = <0x4000 0x8000000>, /* USB0 to SERDES0/3 mux */
 					<0x4010 0x8000000>; /* USB1 to SERDES1/2 mux */
 	    };
+
+		ehrpwm_tbclk: clock@4140 {
+			compatible = "ti,am654-ehrpwm-tbclk", "syscon";
+			reg = <0x4140 0x18>;
+			#clock-cells = <1>;
+		};
 	};
 
 	gic500: interrupt-controller@1800000 {
@@ -2507,4 +2513,58 @@
 		assigned-clocks = <&k3_clks 253 1>;
 		assigned-clock-parents = <&k3_clks 253 5>;
 	};
+
+	ehrpwm0: pwm@3000000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3000000 0x0 0x100>;
+		power-domains = <&k3_pds 83 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 0>, <&k3_clks 83 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm1: pwm@3010000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3010000 0x0 0x100>;
+		power-domains = <&k3_pds 84 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 1>, <&k3_clks 84 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm2: pwm@3020000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3020000 0x0 0x100>;
+		power-domains = <&k3_pds 85 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 2>, <&k3_clks 85 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm3: pwm@3030000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3030000 0x0 0x100>;
+		power-domains = <&k3_pds 86 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 3>, <&k3_clks 86 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm4: pwm@3040000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3040000 0x0 0x100>;
+		power-domains = <&k3_pds 87 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 4>, <&k3_clks 87 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm5: pwm@3050000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3050000 0x0 0x100>;
+		power-domains = <&k3_pds 88 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 5>, <&k3_clks 88 0>;
+		clock-names = "tbclk", "fck";
+	};
 };
-- 
2.17.1

    Exception at Linux boot

    ERROR:   Unhandled External Abort received on 0x80000000 at EL3!
ERROR:    exception reason=0 syndrome=0xbf000000
PANIC in EL3.
x30            = 0x0000000070004644
x0             = 0x0000000000000000
x1             = 0x0000000000000060
x2             = 0x0000000000000060
x3             = 0x0000000000000000
x4             = 0x0000000000000062
x5             = 0x0000000000000008
x6             = 0xffff8008401f0000
x7             = 0x0000000000000000
x8             = 0xffff800842ac2ac0
x9             = 0x0000000041023060
x10            = 0x000000000000073d
x11            = 0x0101010101010101
x12            = 0x0000000000000020
x13            = 0xffff000000000000
x14            = 0x0000000000001c00
x15            = 0x0000000000001400
x16            = 0x0000000000000000
x17            = 0x0000000000000000
x18            = 0xffff8008401f0000
x19            = 0x0000000000000000
x20            = 0x00000000bf000000
x21            = 0xffff0000090cfd14
x22            = 0xffff0000090cfd14
x23            = 0xffff000008d40c20
x24            = 0x0000000000000007
x25            = 0xffff000008e01070
x26            = 0x0000000000000008
x27            = 0xffff000008fa0000
x28            = 0xffff000008d6068c
x29            = 0x000000007000ae20
scr_el3        = 0x000000000000073d
sctlr_el3      = 0x0000000030cd183f
cptr_el3       = 0x0000000000000000
tcr_el3        = 0x0000000080803520
daif           = 0x00000000000002c0
mair_el3       = 0x00000000004404ff
spsr_el3       = 0x0000000020000085
elr_el3        = 0xffff00000864511c
ttbr0_el3      = 0x000000007000f9e0
esr_el3        = 0x00000000bf000000
far_el3        = 0x0000000000000000
spsr_el1       = 0x0000000040000005
elr_el1        = 0xffff0000081163c8
spsr_abt       = 0x0000000000000000
spsr_und       = 0x0000000000000000
spsr_irq       = 0x0000000000000000
spsr_fiq       = 0x0000000000000000
sctlr_el1      = 0x0000000034d5d91d
actlr_el1      = 0x0000000000000000
cpacr_el1      = 0x0000000000300000
csselr_el1     = 0x0000000000000000
sp_el1         = 0xffff0000090cfc40
esr_el1        = 0x0000000096000005
ttbr0_el1      = 0x0000000080f90000
ttbr1_el1      = 0x0000000081070000
mair_el1       = 0x0000bbff440c0400
amair_el1      = 0x0000000000000000
tcr_el1        = 0x00000034f5507510
tpidr_el1      = 0x0000800876c70000
tpidr_el0      = 0x0000000000000000
tpidrro_el0    = 0x0000000000000000
par_el1        = 0x0000000000000000
mpidr_el1      = 0x0000000080000000
afsr0_el1      = 0x0000000000000000
afsr1_el1      = 0x0000000000000000
contextidr_el1 = 0x0000000000000000
vbar_el1       = 0xffff000008081800
cntp_ctl_el0   = 0x0000000000000005
cntp_cval_el0  = 0x000000026bd21c89
cntv_ctl_el0   = 0x0000000000000000
cntv_cval_el0  = 0x0000000000000000
cntkctl_el1    = 0x00000000000000e6
sp_el0         = 0x000000007000ae20
isr_el1        = 0x0000000000000040
dacr32_el2     = 0x0000000000000000
ifsr32_el2     = 0x0000000000000000
cpuectlr_el1   = 0x0000001b00000040
cpumerrsr_el1  = 0x0000000000000000
l2merrsr_el1   = 0x0000000000000000

    Can you please comment on that?

  • 0 in reply to Awais Belal1
    Intellectual 300 points

    Hi Team,

    A response here would be highly appreciated.

  • 0 in reply to Awais Belal1
    TI__Guru**** 155870 points

    Hi Awais,

    I will check with the experts and get back in couple of days.

    Best Regards,
    Keerthy

  • 0 in reply to Keerthy J
    Intellectual 300 points

    Hi Keerthy,

    Thanks a lot. I'll wait for the update.

  • 0 in reply to Awais Belal1
    TI__Guru**** 155870 points

    Hi Awais,

    I looked at: arch/arm64/boot/dts/ti/k3-am65-main.dtsi

            ehrpwm_tbclk: clk0 {
                    compatible = "ti,am654-ehrpwm-tbclk";
                    #clock-cells = <1>;
                    ti,tbclk-syscon = <&tbclk_ctrl>;
            };

    You have additional reg property:

    +
    +       ehrpwm_tbclk: clock@4140 {
    +           compatible = "ti,am654-ehrpwm-tbclk", "syscon";
    +           reg = <0x4140 0x18>;
    +           #clock-cells = <1>;
    +       };

    You should probably knock that off.

    So please try the below diff:

    diff --git a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
index 8675a4887..619532f9e 100644
--- a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
@@ -71,8 +71,74 @@
                        #mux-control-cells = <1>;
                        mux-reg-masks = <0x4000 0x8000000>, /* USB0 to SERDES0/3 mux */
                                        <0x4010 0x8000000>; /* USB1 to SERDES1/2 mux */
-           };
+               };
+
+               tbclk_ctrl: tbclk_ctrl@4140 {
+                       compatible = "syscon";
+                       reg = <0x4140 0x18>;
+               };
+       };
+
+       ehrpwm_tbclk: clk0 {
+               compatible = "ti,am654-ehrpwm-tbclk";
+               #clock-cells = <1>;
+               ti,tbclk-syscon = <&tbclk_ctrl>;
+       };
+
+       ehrpwm0: pwm@3000000 {
+               compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+               #pwm-cells = <3>;
+               reg = <0x0 0x3000000 0x0 0x100>;
+               power-domains = <&k3_pds 83 TI_SCI_PD_EXCLUSIVE>;
+               clocks = <&ehrpwm_tbclk 0>, <&k3_clks 83 0>;
+               clock-names = "tbclk", "fck";
+       };
+
+       ehrpwm1: pwm@3010000 {
+               compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+               #pwm-cells = <3>;
+               reg = <0x0 0x3010000 0x0 0x100>;
+               power-domains = <&k3_pds 84 TI_SCI_PD_EXCLUSIVE>;
+               clocks = <&ehrpwm_tbclk 1>, <&k3_clks 84 0>;
+               clock-names = "tbclk", "fck";
+       };
+
+       ehrpwm2: pwm@3020000 {
+               compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+               #pwm-cells = <3>;
+               reg = <0x0 0x3020000 0x0 0x100>;
+               power-domains = <&k3_pds 85 TI_SCI_PD_EXCLUSIVE>;
+               clocks = <&ehrpwm_tbclk 2>, <&k3_clks 85 0>;
+               clock-names = "tbclk", "fck";
+       };
+
+       ehrpwm3: pwm@3030000 {
+               compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+               #pwm-cells = <3>;
+               reg = <0x0 0x3030000 0x0 0x100>;
+               power-domains = <&k3_pds 86 TI_SCI_PD_EXCLUSIVE>;
+               clocks = <&ehrpwm_tbclk 3>, <&k3_clks 86 0>;
+               clock-names = "tbclk", "fck";
+       };
+
+       ehrpwm4: pwm@3040000 {
+               compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+               #pwm-cells = <3>;
+               reg = <0x0 0x3040000 0x0 0x100>;
+               power-domains = <&k3_pds 87 TI_SCI_PD_EXCLUSIVE>;
+               clocks = <&ehrpwm_tbclk 4>, <&k3_clks 87 0>;
+               clock-names = "tbclk", "fck";
+       };
+
+       ehrpwm5: pwm@3050000 {
+               compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+               #pwm-cells = <3>;
+               reg = <0x0 0x3050000 0x0 0x100>;
+               power-domains = <&k3_pds 88 TI_SCI_PD_EXCLUSIVE>;
+               clocks = <&ehrpwm_tbclk 5>, <&k3_clks 88 0>;
+               clock-names = "tbclk", "fck";
        };
+ };


    Best Regards,
    Keerthy
  • 0 in reply to Keerthy J
    TI__Guru**** 155870 points

    Hello Awais,

    Can you confirm if that is working for you?

    Best Regards,
    Keerthy

  • 0 in reply to Keerthy J
    Intellectual 300 points

    Hi Keerthy,

    Sorry for the delay here. I updated my patch as per your suggestions and it now looks like

    diff --git a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
index 4e04d5b14..3c37b089c 100644
--- a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
@@ -65,6 +65,11 @@
 			mux-reg-masks = <0x4000 0x8000000>, /* USB0 to SERDES0/3 mux */
 					<0x4010 0x8000000>; /* USB1 to SERDES1/2 mux */
 	    };
+
+		tbclk_ctrl: tbclk_ctrl@4140 {
+			compatible = "syscon";
+			reg = <0x4140 0x18>;
+		};
 	};
 
 	gic500: interrupt-controller@1800000 {
@@ -2507,4 +2512,64 @@
 		assigned-clocks = <&k3_clks 253 1>;
 		assigned-clock-parents = <&k3_clks 253 5>;
 	};
+
+	ehrpwm_tbclk: clk0 {
+		compatible = "ti,am654-ehrpwm-tbclk";
+		#clock-cells = <1>;
+		ti,tbclk-syscon = <&tbclk_ctrl>;
+	};
+
+	ehrpwm0: pwm@3000000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3000000 0x0 0x100>;
+		power-domains = <&k3_pds 83 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 0>, <&k3_clks 83 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm1: pwm@3010000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3010000 0x0 0x100>;
+		power-domains = <&k3_pds 84 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 1>, <&k3_clks 84 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm2: pwm@3020000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3020000 0x0 0x100>;
+		power-domains = <&k3_pds 85 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 2>, <&k3_clks 85 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm3: pwm@3030000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3030000 0x0 0x100>;
+		power-domains = <&k3_pds 86 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 3>, <&k3_clks 86 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm4: pwm@3040000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3040000 0x0 0x100>;
+		power-domains = <&k3_pds 87 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 4>, <&k3_clks 87 0>;
+		clock-names = "tbclk", "fck";
+	};
+
+	ehrpwm5: pwm@3050000 {
+		compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
+		#pwm-cells = <3>;
+		reg = <0x0 0x3050000 0x0 0x100>;
+		power-domains = <&k3_pds 88 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&ehrpwm_tbclk 5>, <&k3_clks 88 0>;
+		clock-names = "tbclk", "fck";
+	};
 };
-- 
2.17.1

    However, during boot the probe for the ti-syscon driver (<kernel-source>/drivers/clk/keystone/syscon-clk.c) fails and I get

    # dmesg | grep ti-syscon                                                            
[    0.571881] ti-syscon-gate-clk interconnect@100000:clk0: failed to find parent regmap
[    0.579896] ti-syscon-gate-clk: probe of interconnect@100000:clk0 failed with error -22

    this leads to the ehrpwm driver (<kernel-source>/drivers/pwm/pwm-tiehrpwm.c) failure as no clks are then found

    # dmesg | grep ehrpwm   
[    1.079856] ehrpwm 3000000.pwm: Failed to get tbclk
[    1.085018] ehrpwm 3010000.pwm: Failed to get tbclk
[    1.090177] ehrpwm 3020000.pwm: Failed to get tbclk
[    1.095335] ehrpwm 3030000.pwm: Failed to get tbclk
[    1.100490] ehrpwm 3040000.pwm: Failed to get tbclk
[    1.105648] ehrpwm 3050000.pwm: Failed to get tbclk
...
...
  • 0 in reply to Awais Belal1
    TI__Guru**** 155870 points

    Hi Awais,

    Please have a re-look at your DT. I could probe the device fine and i also have sysfs nodes:

    cat /sys/class/pwm/pwmchip0/
    device/ export npwm power/ subsystem/ uevent unexport
    Best Regards,
    Keerthy
  • 0 in reply to Keerthy J
    Intellectual 300 points

    Hi Keerthy,

    I checked my DT and it conforms to the idea you provided in first post but the result is still the same. One thing that might be the cause is that I am using SDK 06_02 due to some constraints and wouldn't be able to upgrade. Do you envision any further changes with it?

    I think the syscon-clk drivers requires some updates in this case. I'll test and get back on this.

  • 0 in reply to Awais Belal1
    TI__Guru**** 155870 points

    Hi Awais,

    Yes SDK difference could be one. Please let me know once you are done.

    - Keerthy

  • 0 in reply to Keerthy J
    Intellectual 300 points

    Hi Keerthy,

    So I had to pick up a few changes in the syscon-clk driver as expected and I can now see the sys nodes :)

    Thanks for all the help. I'll open a separate ticket if I run into any other run-time issues. This ticket can be closed.

  • 0 in reply to Awais Belal1
    TI__Guru**** 155870 points

    Awais,

    Great! Please resolve the issue.

    Best Regards,
    Keerthy