RE: [RFC PATCH v1 04/14] usb:cdns3: Added DRD support

[Pawel Laszczak <pawell@cadence.com>]

Hi Roger,

>On 03/11/18 19:51, Pawel Laszczak wrote:
>> Patch adds supports for detecting Host/Device mode.
>> Controller has additional OTG register that allow
>> implement even whole OTG functionality.
>> At this moment patch adds support only for detecting
>> the appropriate mode based on strap pins and ID pin.
>>
>> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
>> ---
>>  drivers/usb/cdns3/Makefile |   2 +-
>>  drivers/usb/cdns3/core.c   |  22 ++--
>>  drivers/usb/cdns3/drd.c    | 219 +++++++++++++++++++++++++++++++++++++
>>  drivers/usb/cdns3/drd.h    | 122 +++++++++++++++++++++
>>  4 files changed, 356 insertions(+), 9 deletions(-)
>>  create mode 100644 drivers/usb/cdns3/drd.c
>>  create mode 100644 drivers/usb/cdns3/drd.h
>>
>> diff --git a/drivers/usb/cdns3/Makefile b/drivers/usb/cdns3/Makefile
>> index 083676c7748f..d4ccfb49d844 100644
>> --- a/drivers/usb/cdns3/Makefile
>> +++ b/drivers/usb/cdns3/Makefile
>> @@ -1,7 +1,7 @@
>>  obj-$(CONFIG_USB_CDNS3)			+= cdns3.o
>>  obj-$(CONFIG_USB_CDNS3_PCI_WRAP)	+= cdns3-pci.o
>>
>> -cdns3-y					:= core.o
>> +cdns3-y					:= core.o drd.o
>>  cdns3-$(CONFIG_USB_CDNS3_GADGET)	+= gadget.o
>>  cdns3-$(CONFIG_USB_CDNS3_HOST)		+= host.o
>>  cdns3-pci-y		 		:= cdns3-pci-wrap.o
>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>> index 727136235957..20ae9e76940e 100644
>> --- a/drivers/usb/cdns3/core.c
>> +++ b/drivers/usb/cdns3/core.c
>> @@ -18,6 +18,7 @@
>>  #include "core.h"
>>  #include "host-export.h"
>>  #include "gadget-export.h"
>> +#include "drd.h"
>>
>>  static inline struct cdns3_role_driver *cdns3_role(struct cdns3 *cdns)
>>  {
>> @@ -70,8 +71,10 @@ static void cdns3_set_role(struct cdns3 *cdns, enum cdns3_roles role)
>>  static enum cdns3_roles cdns3_get_role(struct cdns3 *cdns)
>>  {
>>  	if (cdns->roles[CDNS3_ROLE_HOST] && cdns->roles[CDNS3_ROLE_GADGET]) {
>> -		//TODO: implements selecting device/host mode
>> -		return CDNS3_ROLE_HOST;
>> +		if (cdns3_is_host(cdns))
>> +			return CDNS3_ROLE_HOST;
>> +		if (cdns3_is_device(cdns))
>> +			return CDNS3_ROLE_GADGET;
>>  	}
>>  	return cdns->roles[CDNS3_ROLE_HOST]
>>  		? CDNS3_ROLE_HOST
>> @@ -141,6 +144,12 @@ static irqreturn_t cdns3_irq(int irq, void *data)
>>  		return IRQ_HANDLED;
>>  	}
>>
>> +	if (cdns->dr_mode == USB_DR_MODE_OTG) {
>> +		ret = cdns3_drd_irq(cdns);
>> +		if (ret == IRQ_HANDLED)
>> +			return ret;
>> +	}
>> +
>>  	/* Handle device/host interrupt */
>>  	if (cdns->role != CDNS3_ROLE_END)
>>  		ret = cdns3_role(cdns)->irq(cdns);
>> @@ -202,12 +211,8 @@ static void cdns3_role_switch(struct work_struct *work)
>>  	bool device, host;
>>
>>  	cdns = container_of(work, struct cdns3, role_switch_wq);
>> -
>> -	//TODO: implements this functions.
>> -	//host = cdns3_is_host(cdns);
>> -	//device = cdns3_is_device(cdns);
>> -	host = 1;
>> -	device = 0;
>> +	host = cdns3_is_host(cdns);
>> +	device = cdns3_is_device(cdns);
>>
>>  	if (host) {
>>  		if (cdns->roles[CDNS3_ROLE_HOST])
>> @@ -286,6 +291,7 @@ static int cdns3_probe(struct platform_device *pdev)
>>  	if (ret)
>>  		goto err3;
>>
>> +	ret = cdns3_drd_probe(cdns);
>>  	if (ret)
>>  		goto err3;
>>
>> diff --git a/drivers/usb/cdns3/drd.c b/drivers/usb/cdns3/drd.c
>> new file mode 100644
>> index 000000000000..5d988432edb8
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/drd.c
>> @@ -0,0 +1,219 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Cadence USBSS DRD Driver.
>> + *
>> + * Copyright (C) 2018 Cadence.
>> + *
>> + * Author: Pawel Laszczak <pawell@cadence.com
>> + *
>> + */
>> +#include <linux/kernel.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/delay.h>
>> +#include <linux/usb/otg.h>
>> +
>> +#include "gadget.h"
>> +#include "drd.h"
>> +
>> +/**
>> + * cdns3_set_mode - change mode of OTG Core
>> + * @cdns: pointer to context structure
>> + * @mode: selected mode from cdns_role
>> + */
>> +void cdns3_set_mode(struct cdns3 *cdns, u32 mode)
>> +{
>> +	u32 reg;
>> +
>> +	switch (mode) {
>> +	case CDNS3_ROLE_GADGET:
>
>I think we need to make a clear distinction between mode and role.
>
>Mode is the controller mode. (Host-only, Device-only, dual-role[otg])
>Role is the USB controller state (A-Host, B-Device, Idle)

I agree with you,  In next set patch distinction between mode and role will be clear.

>
>cnds->dr_mode should correspond to enum usb_dr_mode which should be the argument
>for this function if you want to set mode.
>
>> +		dev_info(cdns->dev, "Set controller to Gadget mode\n");
>> +		writel(OTGCMD_DEV_BUS_REQ | OTGCMD_OTG_DIS,
>> +		       &cdns->otg_regs->cmd);
>> +		break;
>> +	case CDNS3_ROLE_HOST:
>> +		dev_info(cdns->dev, "Set controller to Host mode\n");
>> +		writel(OTGCMD_HOST_BUS_REQ | OTGCMD_OTG_DIS,
>> +		       &cdns->otg_regs->cmd);
>> +		break;
>> +	case CDNS3_ROLE_OTG:
>> +		dev_info(cdns->dev, "Set controller to OTG mode\n");
>> +		reg = readl(&cdns->otg_regs->ctrl1);
>> +		reg |= OTGCTRL1_IDPULLUP;
>> +		writel(reg, &cdns->otg_regs->ctrl1);
>> +
>> +		/* wait until valid ID (ID_VALUE) can be sampled (50ms). */
>> +		mdelay(50);
>> +		break;
>> +	default:
>> +		dev_err(cdns->dev, "Unsupported mode of operation %d\n", mode);
>> +		return;
>> +	}
>> +}
>> +
>> +static int cdns3_otg_get_id(struct cdns3 *cdns)
>> +{
>> +	int id;
>> +
>> +	id = readl(&cdns->otg_regs->sts) & OTGSTS_ID_VALUE;
>> +	dev_dbg(cdns->dev, "OTG ID: %d", id);
>> +	return id;
>> +}
>> +
>> +int cdns3_is_host(struct cdns3 *cdns)
>> +{
>> +	if (cdns->dr_mode == USB_DR_MODE_HOST)
>> +		return 1;
>
>Why not just use cdns->dr_mode directly?
>
>Do you want to check if it is host role here? e.g. if dr_mode = USB_DR_MODE_OTG.

The function will be slightly completed. 

After corrections:
dr_mode holds the hardware configuration. It will be set during initialization and will not be changed. 
current_dr_mode will hold current mode. This mode can be changed by debugfs. 

This function will look:
 int cdns3_is_host(struct cdns3 *cdns)
{
	if (cdns->current_dr_mode == USB_DR_MODE_HOST)
		return 1;
	else if (cdns->current_dr_mode == USB_DR_MODE_OTG)
		if (!cdns3_otg_get_id(cdns))
			return 1;

	return 0;
}

If DRD mode is set to HOST then always return true, elsewhere it will be based on ID pin. 
So, for USB_DR_MODE_OTG driver will waiting for appropriate role but when 
current_dr_mode == USB_DR_MODE_HOST then we know that only HOST role can be set 
and driver can return true immediately.>
>> +
>> +	return 0;
>> +}
>> +
>> +int cdns3_is_device(struct cdns3 *cdns)
>> +{
>> +	if (cdns->dr_mode == USB_DR_MODE_PERIPHERAL)
>> +		return 1;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * cdns3_otg_disable_irq - Disable all OTG interrupts
>> + * @cdns: Pointer to controller context structure
>> + */
>> +static void cdns3_otg_disable_irq(struct cdns3 *cdns)
>> +{
>> +	writel(0, &cdns->otg_regs->ien);
>> +}
>> +
>> +/**
>> + * cdns3_otg_enable_irq - enable id and sess_valid interrupts
>> + * @cdns: Pointer to controller context structure
>> + */
>> +static void cdns3_otg_enable_irq(struct cdns3 *cdns)
>> +{
>> +	writel(OTGIEN_ID_CHANGE_INT | OTGIEN_VBUSVALID_RISE_INT |
>> +	       OTGIEN_VBUSVALID_FALL_INT, &cdns->otg_regs->ien);
>> +}
>> +
>> +/**
>> + * cdns3_drd_init - initialize drd controller
>> + * @cdns: Pointer to controller context structure
>> + *
>> + * Returns 0 on success otherwise negative errno
>> + */
>> +static void cdns3_drd_init(struct cdns3 *cdns)
>> +{
>> +	cdns3_otg_disable_irq(cdns);
>> +	/* clear all interrupts */
>> +	writel(~0, &cdns->otg_regs->ivect);
>> +
>> +	cdns3_set_mode(cdns, CDNS3_ROLE_OTG);
>> +
>> +	cdns3_otg_enable_irq(cdns);
>> +}
>> +
>> +/**
>> + * cdns3_core_init_mode - initialize mode of operation
>> + * @cdns: Pointer to controller context structure
>> + *
>> + * Returns 0 on success otherwise negative errno
>> + */
>> +static int cdns3_core_init_mode(struct cdns3 *cdns)
>> +{
>> +	int ret = 0;
>> +
>> +	switch (cdns->dr_mode) {
>> +	case USB_DR_MODE_PERIPHERAL:
>> +		cdns3_set_mode(cdns, CDNS3_ROLE_GADGET);
>> +		break;
>> +	case USB_DR_MODE_HOST:
>> +		cdns3_set_mode(cdns, CDNS3_ROLE_HOST);
>> +		break;
>> +	case USB_DR_MODE_OTG:
>> +		cdns3_drd_init(cdns);
>> +		break;
>> +	default:
>> +		dev_err(cdns->dev, "Unsupported mode of operation %d\n",
>> +			cdns->dr_mode);
>> +		return -EINVAL;
>> +	}
>> +
>
>Looks like this function should be on core.c?

The name will be changed to cdns3_drd_update_mode and will be called during initialization, 
or when user change mode by means of debugfs. 
>
>> +	return ret;
>> +}
>> +
>> +irqreturn_t cdns3_drd_irq(struct cdns3 *cdns)
>> +{
>> +	irqreturn_t ret = IRQ_NONE;
>> +	u32 reg;
>> +
>> +	if (cdns->dr_mode != USB_DR_MODE_OTG)
>> +		return ret;
>> +
>> +	reg = readl(&cdns->otg_regs->ivect);
>> +	if (!reg)
>> +		return ret;
>> +
>> +	if (reg & OTGIEN_ID_CHANGE_INT) {
>> +		int id = cdns3_otg_get_id(cdns);
>> +
>> +		dev_dbg(cdns->dev, "OTG IRQ: new ID: %d\n",
>> +			cdns3_otg_get_id(cdns));
>> +
>> +		if (id)
>> +			cdns->desired_role = CDNS3_ROLE_GADGET;
>> +		else
>> +			cdns->desired_role = CDNS3_ROLE_GADGET;
>
>CDNS3_ROLE_HOST.
I found it too and was corrected. 
>> +
>> +		queue_work(system_freezable_wq, &cdns->role_switch_wq);
>> +
>> +		ret = IRQ_HANDLED;
>> +	}
>> +
>> +	writel(~0, &cdns->otg_regs->ivect);
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +int cdns3_drd_probe(struct cdns3 *cdns)
>
>should this be called cdns3_drd_init()?

I changed the name cdns3_drd_init().  I call this cdns3_drd_probe, because I was not sure
whether DRD will be part of whole driver or will be separate driver.  

>> +{
>> +	enum usb_dr_mode dr_mode;
>> +	int ret = 0;
>> +	u32 state;
>> +
>> +	state = OTGSTS_STRAP(readl(&cdns->otg_regs->sts));
>> +
>> +	dr_mode = cdns->dr_mode;
>> +	if (state == OTGSTS_STRAP_HOST) {
>> +		dev_info(cdns->dev, "Controller strapped to HOST\n");
>> +		dr_mode = USB_DR_MODE_HOST;
>> +		if (cdns->dr_mode != USB_DR_MODE_HOST &&
>> +		    cdns->dr_mode != USB_DR_MODE_OTG)
>> +			ret = -EINVAL;
>> +	} else if (state == OTGSTS_STRAP_GADGET) {
>> +		dev_info(cdns->dev, "Controller strapped to HOST\n");
>
>s/HOST/PERIPHERAL? 
>
>> +		dr_mode = USB_DR_MODE_PERIPHERAL;
>> +		if (cdns->dr_mode != USB_DR_MODE_PERIPHERAL &&
>> +		    cdns->dr_mode != USB_DR_MODE_OTG)
>> +			ret = -EINVAL;
>> +	}
>> +
>> +	if (ret) {
>> +		dev_err(cdns->dev, "Incorrect DRD configuration\n");
>> +		return ret;
>> +	}
>> +
>> +	//Updating DR mode according to strap.
>> +	cdns->dr_mode = dr_mode;
>> +
>> +	dev_info(cdns->dev, "Controller Device ID: %08lx, Revision ID: %08lx\n",
>> +		 CDNS_RID(readl(&cdns->otg_regs->rid)),
>> +		 CDNS_DID(readl(&cdns->otg_regs->did)));
>> +
>> +	state = readl(&cdns->otg_regs->sts);
>> +	if (OTGSTS_OTG_NRDY(state) != 0) {
>> +		dev_err(cdns->dev, "Cadence USB3 OTG device not ready\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	ret = cdns3_core_init_mode(cdns);
>> +
>> +	return ret;
>> +}
>> diff --git a/drivers/usb/cdns3/drd.h b/drivers/usb/cdns3/drd.h
>> new file mode 100644
>> index 000000000000..85731f3b693c
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/drd.h
>> @@ -0,0 +1,122 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Cadence USB3 DRD part of USBSS driver
>> + *
>> + * Copyright (C) 2018 Cadence.
>> + *
>> + * Author: Pawel Laszczak <pawell@cadence.com>
>> + */
>> +#ifndef __LINUX_CDNS3_DRD
>> +#define __LINUX_CDNS3_DRD
>> +
>> +#include <linux/usb/otg.h>
>> +#include <linux/phy/phy.h>
>> +#include "core.h"
>> +
>> +/*  DRD register interface. */
>> +struct cdns3_otg_regs {
>> +	__le32 did;
>> +	__le32 rid;
>> +	__le32 capabilities;
>> +	__le32 reserved1;
>> +	__le32 cmd;
>> +	__le32 sts;
>> +	__le32 state;
>> +	__le32 reserved2;
>> +	__le32 ien;
>> +	__le32 ivect;
>> +	__le32 refclk;
>> +	__le32 tmr;
>> +	__le32 reserved3[4];
>> +	__le32 simulate;
>> +	__le32 override;
>> +	__le32 susp_ctrl;
>> +	__le32 reserved4;
>> +	__le32 anasts;
>> +	__le32 adp_ramp_time;
>> +	__le32 ctrl1;
>> +	__le32 ctrl2;
>> +};
>> +
>> +/* CDNS_RID - bitmasks */
>> +#define CDNS_RID(p)			((p) & GENMASK(15, 0))
>> +
>> +/* CDNS_VID - bitmasks */
>> +#define CDNS_DID(p)			((p) & GENMASK(31, 0))
>> +
>> +/* OTGCMD - bitmasks */
>> +/* "Request the bus for Device mode. */
>> +#define OTGCMD_DEV_BUS_REQ	BIT(0)
>> +/* Request the bus for Host mode */
>> +#define OTGCMD_HOST_BUS_REQ		BIT(1)
>> +/* Enable OTG mode. */
>> +#define OTGCMD_OTG_EN			BIT(2)
>> +/* Disable OTG mode */
>> +#define OTGCMD_OTG_DIS			BIT(3)
>> +/*"Configure OTG as A-Device. */
>> +#define OTGCMD_A_DEV_EN			BIT(4)
>> +/*"Configure OTG as A-Device. */
>> +#define OTGCMD_A_DEV_DIS		BIT(5)
>> +/* Drop the bus for Device mod	e. */
>> +#define OTGCMD_DEV_BUS_DROP		BIT(8)
>> +/* Drop the bus for Host mode*/
>> +#define OTGCMD_HOST_BUS_DROP		BIT(9)
>> +/* Power Down USBSS-DEV. */
>> +#define OTGCMD_DEV_POWER_OFF		BIT(11)
>> +/* Power Down CDNSXHCI. */
>> +#define OTGCMD_HOST_POWER_OFF		BIT(12)
>> +
>> +/* OTGIEN - bitmasks */
>> +/* ID change interrupt enable */
>> +#define OTGIEN_ID_CHANGE_INT		BIT(0)
>> +/* Vbusvalid fall detected interrupt enable.*/
>> +#define OTGIEN_VBUSVALID_RISE_INT	BIT(4)
>> +/* Vbusvalid fall detected interrupt enable */
>> +#define OTGIEN_VBUSVALID_FALL_INT	BIT(5)
>> +
>> +/* OTGSTS - bitmasks */
>> +/*
>> + * Current value of the ID pin. It is only valid when idpullup in
>> + *  OTGCTRL1_TYPE register is set to '1'.
>> + */
>> +#define OTGSTS_ID_VALUE			BIT(0)
>> +/* Current value of the vbus_valid */
>> +#define OTGSTS_VBUS_VALID		BIT(1)
>> +/* Current value of the b_sess_vld */
>> +#define OTGSTS_SESSION_VALID		BIT(2)
>> +/*Device mode is active*/
>> +#define OTGSTS_DEV_ACTIVE		BIT(3)
>> +/* Host mode is active. */
>> +#define OTGSTS_HOST_ACTIVE		BIT(4)
>> +/* OTG Controller not ready. */
>> +#define OTGSTS_OTG_NRDY_MASK		BIT(11)
>> +#define OTGSTS_OTG_NRDY(p)		((p) & OTGSTS_OTG_NRDY_MASK)
>> +/*
>> + * Value of the strap pins.
>> + * 000 - no default configuration
>> + * 010 - Controller initiall configured as Host
>> + * 100 - Controller initially configured as Device
>> + */
>> +#define OTGSTS_STRAP(p)			(((p) & GENMASK(14, 12)) >> 12)
>> +#define OTGSTS_STRAP_NO_DEFAULT_CFG	0x00
>> +#define OTGSTS_STRAP_HOST_OTG		0x01
>> +#define OTGSTS_STRAP_HOST		0x02
>> +#define OTGSTS_STRAP_GADGET		0x04
>> +/* Host mode is turned on. */
>> +#define OTGSTSE_XHCI_READYF		BIT(26)
>> +/* "Device mode is turned on .*/
>> +#define OTGSTS_DEV_READY		BIT(27)
>> +
>> +/* OTGREFCLK - bitmasks */
>> +#define OTGREFCLK_STB_CLK_SWITCH_EN	BIT(31)
>> +
>> +/* OTGCTRL1 - bitmasks */
>> +#define OTGCTRL1_IDPULLUP		BIT(24)
>> +
>> +int cdns3_is_host(struct cdns3 *cdns);
>> +int cdns3_is_device(struct cdns3 *cdns);
>> +int cdns3_drd_probe(struct cdns3 *cdns);
>> +void cdns3_set_hw_mode(struct cdns3 *cdns, u32 mode);
>> +irqreturn_t cdns3_drd_irq(struct cdns3 *cdns);
>> +
>> +#endif /* __LINUX_CDNS3_DRD */
>>
>
>cheers,
>-roger
>
>--
>Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Thanks for all your comments
Cheers,
Pawel Laszczak