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Enable HSIC Host Port on Atmel/Microchip SAMA5D2

RFC PATCH In review Alexander Dahl 4 participants 6 messages Aug 23, 2021 – Sep 6, 2021

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USB Arm/Microchip (AT91) SoC support USB ehci driver
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Alexander Dahl

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#0 lore raw

Hello,

for a new embedded board featuring a Microchip SAMA5D2 SoC (64 MiB SiP variant SAMA5D27C-D5M) we connected the third USB host port (HSIC only) with an USB3503 hub chip. This doesn't work out of the box with the Linux kernel currently, because neither the SoC nor the kernel does enable the HSIC interface by default.

That SoC has three USB host ports, from the SAMA5D2 Series Datasheet [1] I learned there's a flag in an EHCI register, which has to be set to enable the HSIC interface on port C, the third port. (Section "41.7.14 EHCI: REG08 - HSIC Enable/Disable" of the datasheet.) I suppose that register is vendor specific. The register definitions in '/include/linux/usb/ehci_def.h' do not contain that register.

Where would I add that register definition and set that flag in the kernel then? I suppose in the vendor specific ehci driver?
That would be 'drivers/usb/host/ehci-atmel.c' right?

Since that feature is optional (other boards don't need to turn on hsic on that port), some driver specific new device tree binding would be necessary, right? I suppose that would have to be documented in 'Documentation/ devicetree/bindings/usb/atmel-usb.txt' right? (Or that would have to be converted to yaml first?)

Is this the right track? If yes, I'm going to develop patches for this. Otherwise any hint into the right direction are highly appreciated.

FWIW, I'm not the first one struggling [2] with this problem. ;-)

Greets
Alex

[1] https://www.microchip.com/en-us/product/ATSAMA5D27C-D5M#document-table
[2] https://community.atmel.com/forum/sama5d2-using-hsic-under-linux

maintainer
#1 lore raw
Quoted 15 lines · Alexander Dahl

Hello,

for a new embedded board featuring a Microchip SAMA5D2 SoC (64 MiB SiP variant SAMA5D27C-D5M) we connected the third USB host port (HSIC only) with an USB3503 hub chip. This doesn't work out of the box with the Linux kernel currently, because neither the SoC nor the kernel does enable the HSIC interface by default.

That SoC has three USB host ports, from the SAMA5D2 Series Datasheet [1] I learned there's a flag in an EHCI register, which has to be set to enable the HSIC interface on port C, the third port. (Section "41.7.14 EHCI: REG08 - HSIC Enable/Disable" of the datasheet.) I suppose that register is vendor specific. The register definitions in '/include/linux/usb/ehci_def.h' do not contain that register.

Quoted 3 lines

Where would I add that register definition and set that flag in the kernel then? I suppose in the vendor specific ehci driver?
That would be 'drivers/usb/host/ehci-atmel.c' right?

That is where you would set the flag. You might want to put the register definition in ehci_def.h, with the other definitions.

Quoted 5 lines

Since that feature is optional (other boards don't need to turn on hsic on that port), some driver specific new device tree binding would be necessary, right? I suppose that would have to be documented in 'Documentation/ devicetree/bindings/usb/atmel-usb.txt' right? (Or that would have to be converted to yaml first?)

Yes, it would have to go into the device tree data somehow. I don't know the best way to do this; people who know more about DT may be able to tell you.

Quoted 2 lines

Is this the right track? If yes, I'm going to develop patches for this. Otherwise any hint into the right direction are highly appreciated.

Yes, this is the right approach.

Alan Stern

Quoted 7 lines

FWIW, I'm not the first one struggling [2] with this problem. ;-)

Greets
Alex

[1] https://www.microchip.com/en-us/product/ATSAMA5D27C-D5M#document-table
[2] https://community.atmel.com/forum/sama5d2-using-hsic-under-linux

author
#2 lore raw

RFC PATCH 1/1 USB: host: ehci-atmel: Allow enabling HSIC on SAMA5D2

Unlike other SoC series featuring the 'atmel,at91sam9g45-ehci' USB EHCI controller, which have embedded USB high-speed transceivers for each port, the third port on the SAMA5D2 series is HSIC only. That HSIC interface is not enabled after a power-on reset, but can be enabled by setting a flag in a vendor specific EHCI register.

The register offsets added to the new header file were compared with those for the SAM9G45, SAM9X25, SAMA5D3, SAMA5D4, and SAM9X60 series and there are no differences in the offsets or contents of those registers. Which of those additional vendor specific registers are supported, differs by SoC family. So while the HSIC enable feature is currently only present for SAMA5D2, it probably does not hurt to set it on the other families, hence no additional check for SoC family here.

Tested on a custom board featuring a SAMA5D27C-D5M SiP connected to an USB3503 hub with an upstream HSIC interface.

Link https://community.atmel.com/forum/sama5d2-using-hsic-under-linux
Signed-off-by Alexander Dahl <[email protected]>

---

Notes:
- for introducing new dt binding, would be nice to convert old one first, probably needs split up and multiple iteration review?
- name of that new dt property?
- register definitions put to a separate file, like 'drivers/usb/host/ehci-fsl.h'
- unsure where exactly in the probe process that register write should happen, datasheet gives no hint
- should suspend/resume be considered?

 drivers/usb/host/ehci-atmel.c | 17 +++++++++++++++++
 drivers/usb/host/ehci-atmel.h | 19 +++++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 drivers/usb/host/ehci-atmel.h
drivers/usb/host/ehci-atmel.c +17 -0
index e893467d659c..f8d9e686c082 100644
@@ -20,6 +20,7 @@
 #include <linux/usb/hcd.h>
 
 #include "ehci.h"
+#include "ehci-atmel.h"
 
 #define DRIVER_DESC "EHCI Atmel driver"
 

@@ -85,6 +86,7 @@ static void atmel_stop_ehci(struct platform_device *pdev)
 
 static int ehci_atmel_drv_probe(struct platform_device *pdev)
 {
+	struct device_node *np = pdev->dev.of_node;
 	struct usb_hcd *hcd;
 	const struct hc_driver *driver = &ehci_atmel_hc_driver;
 	struct resource *res;

@@ -149,6 +151,14 @@ static int ehci_atmel_drv_probe(struct platform_device *pdev)
 
 	atmel_start_ehci(pdev);
 
+	if (of_property_read_bool(np, "atmel,enable-hsic")) {
+		u32 tmp;
+
+		tmp = ehci_readl(ehci, hcd->regs + AT91_UHPHS_INSNREG08);
+		tmp |= AT91_UHPHS_HSIC_EN;
+		ehci_writel(ehci, tmp, hcd->regs + AT91_UHPHS_INSNREG08);
+	}
+
 	retval = usb_add_hcd(hcd, irq, IRQF_SHARED);
 	if (retval)
 		goto fail_add_hcd;

@@ -170,10 +180,17 @@ static int ehci_atmel_drv_probe(struct platform_device *pdev)
 static int ehci_atmel_drv_remove(struct platform_device *pdev)
 {
 	struct usb_hcd *hcd = platform_get_drvdata(pdev);
+	struct ehci_hcd *ehci;
+	u32 tmp;
 
 	usb_remove_hcd(hcd);
 	usb_put_hcd(hcd);
 
+	ehci = hcd_to_ehci(hcd);
+	tmp = ehci_readl(ehci, hcd->regs + AT91_UHPHS_INSNREG08);
+	tmp &= ~AT91_UHPHS_HSIC_EN;
+	ehci_writel(ehci, tmp, hcd->regs + AT91_UHPHS_INSNREG08);
+
 	atmel_stop_ehci(pdev);
 
 	return 0;
drivers/usb/host/ehci-atmel.h new file +19 -0
new file mode 100644
index 000000000000..4c4998c2a6dd
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Vendor specific definitions for EHCI on Atmel/Microchip SoCs.
+ *
+ * © 2021 Alexander Dahl <[email protected]>
+ */
+#ifndef EHCI_ATMEL_H
+#define EHCI_ATMEL_H
+
+/* device specific register offsets, taken from SAMA5D2 datasheet */
+
+#define AT91_UHPHS_INSNREG06    0xA8        /* AHB Error Status Register */
+
+#define AT91_UHPHS_INSNREG07    0xAC        /* AHB Master Error Address Register */
+
+#define AT91_UHPHS_INSNREG08    0xB0        /* HSIC Enable/Disable Register */
+#define AT91_UHPHS_HSIC_EN      (1 << 2)    /* HSIC Enable/Disable */
+
+#endif /* ECHI_ATMEL_H */

base-commit: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93

Signature · 1 line
2.30.2
maintainer
#3 lore raw

Re: [RFC PATCH] USB: host: ehci-atmel: Allow enabling HSIC on SAMA5D2

Quoted 31 lines · Alexander Dahl

Unlike other SoC series featuring the 'atmel,at91sam9g45-ehci' USB EHCI controller, which have embedded USB high-speed transceivers for each port, the third port on the SAMA5D2 series is HSIC only. That HSIC interface is not enabled after a power-on reset, but can be enabled by setting a flag in a vendor specific EHCI register.

The register offsets added to the new header file were compared with those for the SAM9G45, SAM9X25, SAMA5D3, SAMA5D4, and SAM9X60 series and there are no differences in the offsets or contents of those registers. Which of those additional vendor specific registers are supported, differs by SoC family. So while the HSIC enable feature is currently only present for SAMA5D2, it probably does not hurt to set it on the other families, hence no additional check for SoC family here.

Tested on a custom board featuring a SAMA5D27C-D5M SiP connected to an USB3503 hub with an upstream HSIC interface.

Link https://community.atmel.com/forum/sama5d2-using-hsic-under-linux
Signed-off-by Alexander Dahl <[email protected]>

---

Notes:
- for introducing new dt binding, would be nice to convert old one first, probably needs split up and multiple iteration review?
- name of that new dt property?
- register definitions put to a separate file, like 'drivers/usb/host/ehci-fsl.h'
- unsure where exactly in the probe process that register write should happen, datasheet gives no hint
- should suspend/resume be considered?

Quoted 2 lines
 drivers/usb/host/ehci-atmel.c | 17 +++++++++++++++++
 drivers/usb/host/ehci-atmel.h | 19 +++++++++++++++++++

No need for a new .h file that is only used in a single .c file. Just put those few lines in the .c file please.

thanks,

greg k-h

maintainer
#4 lore raw

Re: [RFC PATCH] USB: host: ehci-atmel: Allow enabling HSIC on SAMA5D2

In reply to Alexander Dahl

Hi Alexander,

Quoted 14 lines · Alexander Dahl

Unlike other SoC series featuring the 'atmel,at91sam9g45-ehci' USB EHCI controller, which have embedded USB high-speed transceivers for each port, the third port on the SAMA5D2 series is HSIC only. That HSIC interface is not enabled after a power-on reset, but can be enabled by setting a flag in a vendor specific EHCI register.

The register offsets added to the new header file were compared with those for the SAM9G45, SAM9X25, SAMA5D3, SAMA5D4, and SAM9X60 series and there are no differences in the offsets or contents of those registers. Which of those additional vendor specific registers are supported, differs by SoC family. So while the HSIC enable feature is currently only present for SAMA5D2, it probably does not hurt to set it on the other families, hence no additional check for SoC family here.

Quoted 5 lines

Tested on a custom board featuring a SAMA5D27C-D5M SiP connected to an USB3503 hub with an upstream HSIC interface.

Link https://community.atmel.com/forum/sama5d2-using-hsic-under-linux
Signed-off-by Alexander Dahl <[email protected]>

Sorry for not having coming back to you earlier, summertime...

What you are looking for is what Cristian developed in our "vendor tree" and that needs to be "Mainlined":
https://github.com/linux4sam/linux-at91/commit/ca368f544899c14b03df9ce7510684f03acf1bf9

It allows us to have a gigabit Ethernet HSIC connected on our sama5d2 ICP board. It works well for some time.

For DT, we rely on the standard "phy_type" property set to "hsic" as highlighted in this DT node on the ICP board precisely:
https://github.com/linux4sam/linux-at91/blob/master/arch/arm/boot/dts/at91-sama5d2_icp.dts#L766

This way we can use the of_usb_get_phy_mode() standard function:
https://github.com/linux4sam/linux-at91/blob/master/drivers/usb/phy/of.c#L28

All this tells me that I would prefer Cristi's approach. If agreed, we'll make sure to make progress on the mainlining part soon.

Hope that it helps. Best regards,
Nicolas

Quoted 100 lines

---

Notes:
- for introducing new dt binding, would be nice to convert old one first, probably needs split up and multiple iteration review?
- name of that new dt property?
- register definitions put to a separate file, like 'drivers/usb/host/ehci-fsl.h'
- unsure where exactly in the probe process that register write should happen, datasheet gives no hint
- should suspend/resume be considered?

  drivers/usb/host/ehci-atmel.c | 17 +++++++++++++++++
  drivers/usb/host/ehci-atmel.h | 19 +++++++++++++++++++
  2 files changed, 36 insertions(+)

create mode 100644 drivers/usb/host/ehci-atmel.h

drivers/usb/host/ehci-atmel.c +17 -0
index e893467d659c..f8d9e686c082 100644
@@ -20,6 +20,7 @@
  #include <linux/usb/hcd.h>
 
  #include "ehci.h"
+#include "ehci-atmel.h"
 
  #define DRIVER_DESC "EHCI Atmel driver"
 

@@ -85,6 +86,7 @@ static void atmel_stop_ehci(struct platform_device *pdev)
 
  static int ehci_atmel_drv_probe(struct platform_device *pdev)
  {
+       struct device_node *np = pdev->dev.of_node;
         struct usb_hcd *hcd;
         const struct hc_driver *driver = &ehci_atmel_hc_driver;
         struct resource *res;

@@ -149,6 +151,14 @@ static int ehci_atmel_drv_probe(struct platform_device *pdev)
 
         atmel_start_ehci(pdev);
 
+       if (of_property_read_bool(np, "atmel,enable-hsic")) {
+               u32 tmp;
+
+               tmp = ehci_readl(ehci, hcd->regs + AT91_UHPHS_INSNREG08);
+               tmp |= AT91_UHPHS_HSIC_EN;
+               ehci_writel(ehci, tmp, hcd->regs + AT91_UHPHS_INSNREG08);
+       }
+
         retval = usb_add_hcd(hcd, irq, IRQF_SHARED);
         if (retval)
                 goto fail_add_hcd;

@@ -170,10 +180,17 @@ static int ehci_atmel_drv_probe(struct platform_device *pdev)
  static int ehci_atmel_drv_remove(struct platform_device *pdev)
  {
         struct usb_hcd *hcd = platform_get_drvdata(pdev);
+       struct ehci_hcd *ehci;
+       u32 tmp;
 
         usb_remove_hcd(hcd);
         usb_put_hcd(hcd);
 
+       ehci = hcd_to_ehci(hcd);
+       tmp = ehci_readl(ehci, hcd->regs + AT91_UHPHS_INSNREG08);
+       tmp &= ~AT91_UHPHS_HSIC_EN;
+       ehci_writel(ehci, tmp, hcd->regs + AT91_UHPHS_INSNREG08);
+
         atmel_stop_ehci(pdev);
 
         return 0;
drivers/usb/host/ehci-atmel.h new file +19 -0
new file mode 100644
index 000000000000..4c4998c2a6dd
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Vendor specific definitions for EHCI on Atmel/Microchip SoCs.
+ *
+ * © 2021 Alexander Dahl <[email protected]>
+ */
+#ifndef EHCI_ATMEL_H
+#define EHCI_ATMEL_H
+
+/* device specific register offsets, taken from SAMA5D2 datasheet */
+
+#define AT91_UHPHS_INSNREG06    0xA8        /* AHB Error Status Register */
+
+#define AT91_UHPHS_INSNREG07    0xAC        /* AHB Master Error Address Register */
+
+#define AT91_UHPHS_INSNREG08    0xB0        /* HSIC Enable/Disable Register */
+#define AT91_UHPHS_HSIC_EN      (1 << 2)    /* HSIC Enable/Disable */
+
+#endif /* ECHI_ATMEL_H */

base-commit: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93 --
2.30.2

Signature · 1 line
Nicolas Ferre
author
#5 lore raw

Re: [RFC PATCH] USB: host: ehci-atmel: Allow enabling HSIC on SAMA5D2

Hello Nicolas,

Am Donnerstag, 2. September 2021, 17:33:50 CEST schrieb Nicolas Ferre:

Quoted 17 lines

Hi Alexander,

Quoted 14 lines · Alexander Dahl

Unlike other SoC series featuring the 'atmel,at91sam9g45-ehci' USB EHCI controller, which have embedded USB high-speed transceivers for each port, the third port on the SAMA5D2 series is HSIC only. That HSIC interface is not enabled after a power-on reset, but can be enabled by setting a flag in a vendor specific EHCI register.

The register offsets added to the new header file were compared with those for the SAM9G45, SAM9X25, SAMA5D3, SAMA5D4, and SAM9X60 series and there are no differences in the offsets or contents of those registers. Which of those additional vendor specific registers are supported, differs by SoC family. So while the HSIC enable feature is currently only present for SAMA5D2, it probably does not hurt to set it on the other families, hence no additional check for SoC family here.

Quoted 7 lines
Quoted 5 lines

Tested on a custom board featuring a SAMA5D27C-D5M SiP connected to an USB3503 hub with an upstream HSIC interface.

Link https://community.atmel.com/forum/sama5d2-using-hsic-under-linux
Signed-off-by Alexander Dahl <[email protected]>

Sorry for not having coming back to you earlier, summertime...

I had one week off last week due to a mild infection myself, so we just proceed here and now. (-:

Quoted 4 lines

What you are looking for is what Cristian developed in our "vendor tree" and that needs to be "Mainlined":
https://github.com/linux4sam/linux-at91/commit/ca368f544899c14b03df9ce751068
4f03acf1bf9

Looks like it does what it should from quick code inspection. One could nitpick some things, maybe I add some comments on GitHub.

Quoted 2 lines

It allows us to have a gigabit Ethernet HSIC connected on our sama5d2 ICP board. It works well for some time.

Good to hear.

Quoted 7 lines

For DT, we rely on the standard "phy_type" property set to "hsic" as highlighted in this DT node on the ICP board precisely:
https://github.com/linux4sam/linux-at91/blob/master/arch/arm/boot/dts/at91-s
ama5d2_icp.dts#L766

This way we can use the of_usb_get_phy_mode() standard function:
https://github.com/linux4sam/linux-at91/blob/master/drivers/usb/phy/of.c#L28

I noticed that phy_type property, but did not follow that approach, because that USB block in SAMA5D2 has three ports, where one (A) is shared with a device port, two (A and B) have embedded transceivers, and only the third (C) has that HSIC interface, but nothing else. So the flag has no effect on port A and B anyways, and I would have found it misleading to set phy_type to HSIC for the whole USB block.

Quoted 2 lines

All this tells me that I would prefer Cristi's approach. If agreed, we'll make sure to make progress on the mainlining part soon.

I don't mind. If that's your preferred approach, I will happily test it. Was the series already posted to upstream?

Quoted 2 lines

Hope that it helps. Best regards,
Nicolas

Yes, indeed. Thanks for your feedback.

Greets
Alex

Quoted 121 lines
Quoted 121 lines

---

Notes:
- for introducing new dt binding, would be nice to convert old one

first, probably needs split up and multiple iteration review?

- name of that new dt property?
- register definitions put to a separate file, like

'drivers/usb/host/ehci-fsl.h'

- unsure where exactly in the probe process that register write should

happen, datasheet gives no hint

- should suspend/resume be considered?

  drivers/usb/host/ehci-atmel.c | 17 +++++++++++++++++
  drivers/usb/host/ehci-atmel.h | 19 +++++++++++++++++++
  2 files changed, 36 insertions(+)

create mode 100644 drivers/usb/host/ehci-atmel.h

drivers/usb/host/ehci-atmel.c +1 -0
index e893467d659c..f8d9e686c082 100644
@@ -20,6 +20,7 @@
 
  #include <linux/usb/hcd.h>
 
  #include "ehci.h"
 
+#include "ehci-atmel.h"
 

  #define DRIVER_DESC "EHCI Atmel driver"
drivers/usb/host/ehci-atmel.c +1 -0
@@ -85,6 +86,7 @@ static void atmel_stop_ehci(struct platform_device
 *pdev)
 
  static int ehci_atmel_drv_probe(struct platform_device *pdev)
  {
 
+       struct device_node *np = pdev->dev.of_node;
 

         struct usb_hcd *hcd;
         const struct hc_driver *driver = &ehci_atmel_hc_driver;
         struct resource *res;
drivers/usb/host/ehci-atmel.c +0 -0
@@ -149,6 +151,14 @@ static int ehci_atmel_drv_probe(struct

platform_device *pdev)>

         atmel_start_ehci(pdev);
drivers/usb/host/ehci-atmel.c +8 -0
+       if (of_property_read_bool(np, "atmel,enable-hsic")) {
+               u32 tmp;
+
+               tmp = ehci_readl(ehci, hcd->regs + AT91_UHPHS_INSNREG08);
+               tmp |= AT91_UHPHS_HSIC_EN;
+               ehci_writel(ehci, tmp, hcd->regs + AT91_UHPHS_INSNREG08);
+       }
+
 
         retval = usb_add_hcd(hcd, irq, IRQF_SHARED);
         if (retval)
 
                 goto fail_add_hcd;

@@ -170,10 +180,17 @@ static int ehci_atmel_drv_probe(struct

platform_device *pdev)>
static int ehci_atmel_drv_remove(struct platform_device *pdev) {

         struct usb_hcd *hcd = platform_get_drvdata(pdev);
drivers/usb/host/ehci-atmel.c +7 -0
+       struct ehci_hcd *ehci;
+       u32 tmp;
 
         usb_remove_hcd(hcd);
         usb_put_hcd(hcd);
 
+       ehci = hcd_to_ehci(hcd);
+       tmp = ehci_readl(ehci, hcd->regs + AT91_UHPHS_INSNREG08);
+       tmp &= ~AT91_UHPHS_HSIC_EN;
+       ehci_writel(ehci, tmp, hcd->regs + AT91_UHPHS_INSNREG08);
+
 
         atmel_stop_ehci(pdev);
 
         return 0;
drivers/usb/host/ehci-atmel.h new file +12 -0
new file mode 100644
index 000000000000..4c4998c2a6dd
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Vendor specific definitions for EHCI on Atmel/Microchip SoCs.
+ *
+ * © 2021 Alexander Dahl <[email protected]>
+ */
+#ifndef EHCI_ATMEL_H
+#define EHCI_ATMEL_H
+
+/* device specific register offsets, taken from SAMA5D2 datasheet */
+
+#define AT91_UHPHS_INSNREG06    0xA8        /* AHB Error Status Register

*/ +
+#define AT91_UHPHS_INSNREG07 0xAC /* AHB Master Error Address
Register */ +
+#define AT91_UHPHS_INSNREG08 0xB0 /* HSIC Enable/Disable
Register */ +#define AT91_UHPHS_HSIC_EN (1 << 2) /* HSIC
Enable/Disable */ +
+#endif /* ECHI_ATMEL_H */

base-commit: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93 --
2.30.2