Instead of relying on the vendor specific implementations to send the
PME_Turn_Off message, let's introduce a generic way of sending the message
using the MSG TLP.

This is achieved by reserving a region for MSG TLP of size
'pci->region_align', at the end of the first IORESOURCE_MEM window of the
host bridge. And then sending the PME_Turn_Off message during system
suspend with the help of iATU.

The reserve space at end is a little bit better than alloc_resource()
because the below reasons.
- alloc_resource() will allocate space at begin of IORESOURCE_MEM window.
There will be a hole when first Endpoint Device (EP) try to alloc a bigger
space then 'region_align' size.
- Keep EP device's IORESOURCE_MEM space unchange with/without this patch.

It should be noted that this generic implementation is optional for the
glue drivers and can be overridden by a custom 'pme_turn_off' callback.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 94 ++++++++++++++++++++++-
 drivers/pci/controller/dwc/pcie-designware.h      |  3 +
 2 files changed, 93 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 3a9cb4be22ab2..5001cdf220123 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -398,6 +398,31 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
 	return 0;
 }
 
+static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct resource_entry *win;
+	struct resource *res;
+
+	win = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
+	if (win) {
+		res = devm_kzalloc(pci->dev, sizeof(*res), GFP_KERNEL);
+		if (!res)
+			return;
+
+		/* Reserve last region_align block as message TLP space */
+		res->start = win->res->end - pci->region_align + 1;
+		res->end = win->res->end;
+		res->name = "msg";
+		res->flags = win->res->flags | IORESOURCE_BUSY;
+
+		if (!devm_request_resource(pci->dev, win->res, res))
+			pp->msg_res = res;
+		else
+			devm_kfree(pci->dev, res);
+	}
+}
+
 int dw_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -484,6 +509,16 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
 
 	dw_pcie_iatu_detect(pci);
 
+	/*
+	 * Allocate the resource for MSG TLP before programming the iATU outbound window in
+	 * dw_pcie_setup_rc(). Since the allocation depends on the value of 'region_align', this has
+	 * to be done after dw_pcie_iatu_detect().
+	 *
+	 * Glue driver need set use_atu_msg before dw_pcie_host_init() if want MSG TLP feature.
+	 */
+	if (pp->use_atu_msg)
+		dw_pcie_host_request_msg_tlp_res(pp);
+
 	ret = dw_pcie_edma_detect(pci);
 	if (ret)
 		goto err_free_msi;
@@ -541,6 +576,11 @@ void dw_pcie_host_deinit(struct dw_pcie_rp *pp)
 
 	dw_pcie_edma_remove(pci);
 
+	if (pp->msg_res) {
+		release_resource(pp->msg_res);
+		devm_kfree(pci->dev, pp->msg_res);
+	}
+
 	if (pp->has_msi_ctrl)
 		dw_pcie_free_msi(pp);
 
@@ -702,6 +742,10 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
 		atu.pci_addr = entry->res->start - entry->offset;
 		atu.size = resource_size(entry->res);
 
+		/* MSG TLB window resource reserve at one of end of IORESOURCE_MEM resource */
+		if (pp->msg_res && pp->msg_res->parent == entry->res)
+			atu.size -= resource_size(pp->msg_res);
+
 		ret = dw_pcie_prog_outbound_atu(pci, &atu);
 		if (ret) {
 			dev_err(pci->dev, "Failed to set MEM range %pr\n",
@@ -733,6 +777,8 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
 		dev_warn(pci->dev, "Ranges exceed outbound iATU size (%d)\n",
 			 pci->num_ob_windows);
 
+	pp->msg_atu_index = i;
+
 	i = 0;
 	resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {
 		if (resource_type(entry->res) != IORESOURCE_MEM)
@@ -838,11 +884,48 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
 }
 EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
 
+/* Using message outbound ATU to send out PME_Turn_Off message for dwc PCIe controller */
+static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
+{
+	struct dw_pcie_ob_atu_cfg atu = { 0 };
+	void __iomem *mem;
+	int ret;
+
+	if (pci->num_ob_windows <= pci->pp.msg_atu_index)
+		return -EINVAL;
+
+	if (!pci->pp.msg_res)
+		return -EINVAL;
+
+	atu.code = PCIE_MSG_CODE_PME_TURN_OFF;
+	atu.routing = PCIE_MSG_TYPE_R_BC;
+	atu.type = PCIE_ATU_TYPE_MSG;
+	atu.size = resource_size(pci->pp.msg_res);
+	atu.index = pci->pp.msg_atu_index;
+
+	atu.cpu_addr = pci->pp.msg_res->start;
+
+	ret = dw_pcie_prog_outbound_atu(pci, &atu);
+	if (ret)
+		return ret;
+
+	mem = ioremap(atu.cpu_addr, pci->region_align);
+	if (!mem)
+		return -ENOMEM;
+
+	/* A dummy write is converted to a Msg TLP */
+	writel(0, mem);
+
+	iounmap(mem);
+
+	return 0;
+}
+
 int dw_pcie_suspend_noirq(struct dw_pcie *pci)
 {
 	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
 	u32 val;
-	int ret;
+	int ret = 0;
 
 	/*
 	 * If L1SS is supported, then do not put the link into L2 as some
@@ -854,10 +937,13 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
 	if (dw_pcie_get_ltssm(pci) <= DW_PCIE_LTSSM_DETECT_ACT)
 		return 0;
 
-	if (!pci->pp.ops->pme_turn_off)
-		return 0;
+	if (pci->pp.ops->pme_turn_off)
+		pci->pp.ops->pme_turn_off(&pci->pp);
+	else
+		ret = dw_pcie_pme_turn_off(pci);
 
-	pci->pp.ops->pme_turn_off(&pci->pp);
+	if (ret)
+		return ret;
 
 	ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
 				PCIE_PME_TO_L2_TIMEOUT_US/10,
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 703b50bc5e0f1..dca5de4c6e877 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -341,6 +341,9 @@ struct dw_pcie_rp {
 	struct pci_host_bridge  *bridge;
 	raw_spinlock_t		lock;
 	DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
+	bool			use_atu_msg;
+	int			msg_atu_index;
+	struct resource		*msg_res;
 };
 
 struct dw_pcie_ep_ops {

-- 
2.34.1

On Mon, Apr 15, 2024 at 03:33:29PM -0400, Frank Li wrote:
> Instead of relying on the vendor specific implementations to send the
> PME_Turn_Off message, let's introduce a generic way of sending the message
> using the MSG TLP.
> 
> This is achieved by reserving a region for MSG TLP of size
> 'pci->region_align', at the end of the first IORESOURCE_MEM window of the
> host bridge. And then sending the PME_Turn_Off message during system
> suspend with the help of iATU.
> 
> The reserve space at end is a little bit better than alloc_resource()
> because the below reasons.
> - alloc_resource() will allocate space at begin of IORESOURCE_MEM window.
> There will be a hole when first Endpoint Device (EP) try to alloc a bigger
> space then 'region_align' size.
> - Keep EP device's IORESOURCE_MEM space unchange with/without this patch.
> 

I'd rewrite the above sentence as:

'The reason for reserving the MSG TLP region at the end of the
IORESOURCE_MEM is to avoid generating holes in between. Because, when the region
is allocated using allocate_resource(), memory will be allocated from the start
of the window. Later, if memory gets allocated for an endpoint of size bigger
than 'region_align', there will be a hole between MSG TLP region and endpoint
memory.'

> It should be noted that this generic implementation is optional for the
> glue drivers and can be overridden by a custom 'pme_turn_off' callback.
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 94 ++++++++++++++++++++++-
>  drivers/pci/controller/dwc/pcie-designware.h      |  3 +
>  2 files changed, 93 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 3a9cb4be22ab2..5001cdf220123 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -398,6 +398,31 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
>  	return 0;
>  }
>  
> +static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct resource_entry *win;
> +	struct resource *res;
> +
> +	win = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
> +	if (win) {
> +		res = devm_kzalloc(pci->dev, sizeof(*res), GFP_KERNEL);
> +		if (!res)
> +			return;
> +
> +		/* Reserve last region_align block as message TLP space */

		/*
		 * Allocate MSG TLP region of size 'region_align' at the end of
		 * the host bridge window.
		 */

> +		res->start = win->res->end - pci->region_align + 1;
> +		res->end = win->res->end;
> +		res->name = "msg";
> +		res->flags = win->res->flags | IORESOURCE_BUSY;
> +
> +		if (!devm_request_resource(pci->dev, win->res, res))
> +			pp->msg_res = res;
> +		else
> +			devm_kfree(pci->dev, res);

You are explicitly freeing 'msg_res' everywhere. So either drop devm_ or rely
on devm to free the memory.

> +	}
> +}
> +
>  int dw_pcie_host_init(struct dw_pcie_rp *pp)
>  {
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> @@ -484,6 +509,16 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
>  
>  	dw_pcie_iatu_detect(pci);
>  
> +	/*
> +	 * Allocate the resource for MSG TLP before programming the iATU outbound window in
> +	 * dw_pcie_setup_rc(). Since the allocation depends on the value of 'region_align', this has
> +	 * to be done after dw_pcie_iatu_detect().

Please wrap the comments to 80 columns.

> +	 *
> +	 * Glue driver need set use_atu_msg before dw_pcie_host_init() if want MSG TLP feature.

How about,

	 * Glue drivers need to set 'use_atu_msg' before dw_pcie_host_init() to
	 * make use of the generic MSG TLP implementation.

> +	 */
> +	if (pp->use_atu_msg)
> +		dw_pcie_host_request_msg_tlp_res(pp);
> +
>  	ret = dw_pcie_edma_detect(pci);
>  	if (ret)
>  		goto err_free_msi;
> @@ -541,6 +576,11 @@ void dw_pcie_host_deinit(struct dw_pcie_rp *pp)
>  
>  	dw_pcie_edma_remove(pci);
>  
> +	if (pp->msg_res) {
> +		release_resource(pp->msg_res);
> +		devm_kfree(pci->dev, pp->msg_res);
> +	}
> +
>  	if (pp->has_msi_ctrl)
>  		dw_pcie_free_msi(pp);
>  
> @@ -702,6 +742,10 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
>  		atu.pci_addr = entry->res->start - entry->offset;
>  		atu.size = resource_size(entry->res);
>  
> +		/* MSG TLB window resource reserve at one of end of IORESOURCE_MEM resource */

How about,

		/* Adjust iATU size if MSG TLP region was allocated before */
		if (pp->msg_res && pp->msg_res->parent == entry->res)
			atu.size = resource_size(entry->res) -
					resource_size(pp->msg_res);
		else
			atu.size = resource_size(entry->res);

> +		if (pp->msg_res && pp->msg_res->parent == entry->res)
> +			atu.size -= resource_size(pp->msg_res);
> +
>  		ret = dw_pcie_prog_outbound_atu(pci, &atu);
>  		if (ret) {
>  			dev_err(pci->dev, "Failed to set MEM range %pr\n",
> @@ -733,6 +777,8 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
>  		dev_warn(pci->dev, "Ranges exceed outbound iATU size (%d)\n",
>  			 pci->num_ob_windows);
>  
> +	pp->msg_atu_index = i;
> +
>  	i = 0;
>  	resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {
>  		if (resource_type(entry->res) != IORESOURCE_MEM)
> @@ -838,11 +884,48 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
>  }
>  EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
>  
> +/* Using message outbound ATU to send out PME_Turn_Off message for dwc PCIe controller */

No need of this comment.

> +static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
> +{
> +	struct dw_pcie_ob_atu_cfg atu = { 0 };
> +	void __iomem *mem;
> +	int ret;
> +
> +	if (pci->num_ob_windows <= pci->pp.msg_atu_index)
> +		return -EINVAL;

		return -ENOSPC;

> +
> +	if (!pci->pp.msg_res)
> +		return -EINVAL;

		return -ENOSPC;
- Mani

-- 
மணிவண்ணன் சதாசிவம்

On Wed, Apr 17, 2024 at 03:49:44PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Apr 15, 2024 at 03:33:29PM -0400, Frank Li wrote:
> > Instead of relying on the vendor specific implementations to send the
> > PME_Turn_Off message, let's introduce a generic way of sending the message
> > using the MSG TLP.
> > 
> > This is achieved by reserving a region for MSG TLP of size
> > 'pci->region_align', at the end of the first IORESOURCE_MEM window of the
> > host bridge. And then sending the PME_Turn_Off message during system
> > suspend with the help of iATU.
> > 
> > The reserve space at end is a little bit better than alloc_resource()
> > because the below reasons.
> > - alloc_resource() will allocate space at begin of IORESOURCE_MEM window.
> > There will be a hole when first Endpoint Device (EP) try to alloc a bigger
> > space then 'region_align' size.
> > - Keep EP device's IORESOURCE_MEM space unchange with/without this patch.
> > 
> 
> I'd rewrite the above sentence as:
> 
> 'The reason for reserving the MSG TLP region at the end of the
> IORESOURCE_MEM is to avoid generating holes in between. Because, when the region
> is allocated using allocate_resource(), memory will be allocated from the start
> of the window. Later, if memory gets allocated for an endpoint of size bigger
> than 'region_align', there will be a hole between MSG TLP region and endpoint
> memory.'
> 
> > It should be noted that this generic implementation is optional for the
> > glue drivers and can be overridden by a custom 'pme_turn_off' callback.
> > 
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> >  drivers/pci/controller/dwc/pcie-designware-host.c | 94 ++++++++++++++++++++++-
> >  drivers/pci/controller/dwc/pcie-designware.h      |  3 +
> >  2 files changed, 93 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > index 3a9cb4be22ab2..5001cdf220123 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -398,6 +398,31 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
> >  	return 0;
> >  }
> >  
> > +static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
> > +{
> > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > +	struct resource_entry *win;
> > +	struct resource *res;
> > +
> > +	win = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
> > +	if (win) {
> > +		res = devm_kzalloc(pci->dev, sizeof(*res), GFP_KERNEL);
> > +		if (!res)
> > +			return;
> > +
> > +		/* Reserve last region_align block as message TLP space */
> 
> 		/*
> 		 * Allocate MSG TLP region of size 'region_align' at the end of
> 		 * the host bridge window.
> 		 */
> 
> > +		res->start = win->res->end - pci->region_align + 1;
> > +		res->end = win->res->end;
> > +		res->name = "msg";
> > +		res->flags = win->res->flags | IORESOURCE_BUSY;
> > +
> > +		if (!devm_request_resource(pci->dev, win->res, res))
> > +			pp->msg_res = res;
> > +		else
> > +			devm_kfree(pci->dev, res);
> 
> You are explicitly freeing 'msg_res' everywhere. So either drop devm_ or rely
> on devm to free the memory.
> 
> > +	}
> > +}
> > +
> >  int dw_pcie_host_init(struct dw_pcie_rp *pp)
> >  {
> >  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > @@ -484,6 +509,16 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> >  
> >  	dw_pcie_iatu_detect(pci);
> >  
> > +	/*
> > +	 * Allocate the resource for MSG TLP before programming the iATU outbound window in
> > +	 * dw_pcie_setup_rc(). Since the allocation depends on the value of 'region_align', this has
> > +	 * to be done after dw_pcie_iatu_detect().
> 
> Please wrap the comments to 80 columns.

New code style is 100 columns. does comments still stick to 80 columns?

> 
> > +	 *
> > +	 * Glue driver need set use_atu_msg before dw_pcie_host_init() if want MSG TLP feature.
> 
> How about,
> 
> 	 * Glue drivers need to set 'use_atu_msg' before dw_pcie_host_init() to
> 	 * make use of the generic MSG TLP implementation.
> 
> > +	 */
> > +	if (pp->use_atu_msg)
> > +		dw_pcie_host_request_msg_tlp_res(pp);
> > +
> >  	ret = dw_pcie_edma_detect(pci);
> >  	if (ret)
> >  		goto err_free_msi;
> > @@ -541,6 +576,11 @@ void dw_pcie_host_deinit(struct dw_pcie_rp *pp)
> >  
> >  	dw_pcie_edma_remove(pci);
> >  
> > +	if (pp->msg_res) {
> > +		release_resource(pp->msg_res);
> > +		devm_kfree(pci->dev, pp->msg_res);
> > +	}
> > +
> >  	if (pp->has_msi_ctrl)
> >  		dw_pcie_free_msi(pp);
> >  
> > @@ -702,6 +742,10 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> >  		atu.pci_addr = entry->res->start - entry->offset;
> >  		atu.size = resource_size(entry->res);
> >  
> > +		/* MSG TLB window resource reserve at one of end of IORESOURCE_MEM resource */
> 
> How about,
> 
> 		/* Adjust iATU size if MSG TLP region was allocated before */
> 		if (pp->msg_res && pp->msg_res->parent == entry->res)
> 			atu.size = resource_size(entry->res) -
> 					resource_size(pp->msg_res);
> 		else
> 			atu.size = resource_size(entry->res);
> 
> > +		if (pp->msg_res && pp->msg_res->parent == entry->res)
> > +			atu.size -= resource_size(pp->msg_res);
> > +
> >  		ret = dw_pcie_prog_outbound_atu(pci, &atu);
> >  		if (ret) {
> >  			dev_err(pci->dev, "Failed to set MEM range %pr\n",
> > @@ -733,6 +777,8 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> >  		dev_warn(pci->dev, "Ranges exceed outbound iATU size (%d)\n",
> >  			 pci->num_ob_windows);
> >  
> > +	pp->msg_atu_index = i;
> > +
> >  	i = 0;
> >  	resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {
> >  		if (resource_type(entry->res) != IORESOURCE_MEM)
> > @@ -838,11 +884,48 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
> >  }
> >  EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
> >  
> > +/* Using message outbound ATU to send out PME_Turn_Off message for dwc PCIe controller */
> 
> No need of this comment.
> 
> > +static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
> > +{
> > +	struct dw_pcie_ob_atu_cfg atu = { 0 };
> > +	void __iomem *mem;
> > +	int ret;
> > +
> > +	if (pci->num_ob_windows <= pci->pp.msg_atu_index)
> > +		return -EINVAL;
> 
> 		return -ENOSPC;
> 
> > +
> > +	if (!pci->pp.msg_res)
> > +		return -EINVAL;
> 
> 		return -ENOSPC;
> - Mani
> 
> -- 
> மணிவண்ணன் சதாசிவம்

On Wed, Apr 17, 2024 at 10:38:04AM -0400, Frank Li wrote:
> On Wed, Apr 17, 2024 at 03:49:44PM +0530, Manivannan Sadhasivam wrote:
> > On Mon, Apr 15, 2024 at 03:33:29PM -0400, Frank Li wrote:
> > > +	/*
> > > +	 * Allocate the resource for MSG TLP before programming the iATU outbound window in
> > > +	 * dw_pcie_setup_rc(). Since the allocation depends on the value of 'region_align', this has
> > > +	 * to be done after dw_pcie_iatu_detect().
> > 
> > Please wrap the comments to 80 columns.
> 
> New code style is 100 columns. does comments still stick to 80 columns?

I care more about files being consistent internally than I do about
adhering to a new 100 column rule.

With very few exceptions, pcie-designware-host.c fits in 80 columns.
I think there's no point in adding a comment using 100 columns.  That
leadds to either a window sized to accommodate 100 columns, where 20
columns are wasted for all the existing code and comments, or a window
sized for 80 columns, where the new comment looks ugly.  Neither is
attractive.

Bjorn

On Wed, Apr 17, 2024 at 10:38:04AM -0400, Frank Li wrote:
> On Wed, Apr 17, 2024 at 03:49:44PM +0530, Manivannan Sadhasivam wrote:
> > On Mon, Apr 15, 2024 at 03:33:29PM -0400, Frank Li wrote:
> > > Instead of relying on the vendor specific implementations to send the
> > > PME_Turn_Off message, let's introduce a generic way of sending the message
> > > using the MSG TLP.
> > > 
> > > This is achieved by reserving a region for MSG TLP of size
> > > 'pci->region_align', at the end of the first IORESOURCE_MEM window of the
> > > host bridge. And then sending the PME_Turn_Off message during system
> > > suspend with the help of iATU.
> > > 
> > > The reserve space at end is a little bit better than alloc_resource()
> > > because the below reasons.
> > > - alloc_resource() will allocate space at begin of IORESOURCE_MEM window.
> > > There will be a hole when first Endpoint Device (EP) try to alloc a bigger
> > > space then 'region_align' size.
> > > - Keep EP device's IORESOURCE_MEM space unchange with/without this patch.
> > > 
> > 
> > I'd rewrite the above sentence as:
> > 
> > 'The reason for reserving the MSG TLP region at the end of the
> > IORESOURCE_MEM is to avoid generating holes in between. Because, when the region
> > is allocated using allocate_resource(), memory will be allocated from the start
> > of the window. Later, if memory gets allocated for an endpoint of size bigger
> > than 'region_align', there will be a hole between MSG TLP region and endpoint
> > memory.'
> > 
> > > It should be noted that this generic implementation is optional for the
> > > glue drivers and can be overridden by a custom 'pme_turn_off' callback.
> > > 
> > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > > ---
> > >  drivers/pci/controller/dwc/pcie-designware-host.c | 94 ++++++++++++++++++++++-
> > >  drivers/pci/controller/dwc/pcie-designware.h      |  3 +
> > >  2 files changed, 93 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > > index 3a9cb4be22ab2..5001cdf220123 100644
> > > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > > @@ -398,6 +398,31 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
> > >  	return 0;
> > >  }
> > >  
> > > +static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
> > > +{
> > > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > +	struct resource_entry *win;
> > > +	struct resource *res;
> > > +
> > > +	win = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
> > > +	if (win) {
> > > +		res = devm_kzalloc(pci->dev, sizeof(*res), GFP_KERNEL);
> > > +		if (!res)
> > > +			return;
> > > +
> > > +		/* Reserve last region_align block as message TLP space */
> > 
> > 		/*
> > 		 * Allocate MSG TLP region of size 'region_align' at the end of
> > 		 * the host bridge window.
> > 		 */
> > 
> > > +		res->start = win->res->end - pci->region_align + 1;
> > > +		res->end = win->res->end;
> > > +		res->name = "msg";
> > > +		res->flags = win->res->flags | IORESOURCE_BUSY;
> > > +
> > > +		if (!devm_request_resource(pci->dev, win->res, res))
> > > +			pp->msg_res = res;
> > > +		else
> > > +			devm_kfree(pci->dev, res);
> > 
> > You are explicitly freeing 'msg_res' everywhere. So either drop devm_ or rely
> > on devm to free the memory.
> > 
> > > +	}
> > > +}
> > > +
> > >  int dw_pcie_host_init(struct dw_pcie_rp *pp)
> > >  {
> > >  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > @@ -484,6 +509,16 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> > >  
> > >  	dw_pcie_iatu_detect(pci);
> > >  
> > > +	/*
> > > +	 * Allocate the resource for MSG TLP before programming the iATU outbound window in
> > > +	 * dw_pcie_setup_rc(). Since the allocation depends on the value of 'region_align', this has
> > > +	 * to be done after dw_pcie_iatu_detect().
> > 
> > Please wrap the comments to 80 columns.
> 
> New code style is 100 columns. does comments still stick to 80 columns?
> 

That's only applicable for code and not comments. I also learned that some time
back.

- Mani

> > 
> > > +	 *
> > > +	 * Glue driver need set use_atu_msg before dw_pcie_host_init() if want MSG TLP feature.
> > 
> > How about,
> > 
> > 	 * Glue drivers need to set 'use_atu_msg' before dw_pcie_host_init() to
> > 	 * make use of the generic MSG TLP implementation.
> > 
> > > +	 */
> > > +	if (pp->use_atu_msg)
> > > +		dw_pcie_host_request_msg_tlp_res(pp);
> > > +
> > >  	ret = dw_pcie_edma_detect(pci);
> > >  	if (ret)
> > >  		goto err_free_msi;
> > > @@ -541,6 +576,11 @@ void dw_pcie_host_deinit(struct dw_pcie_rp *pp)
> > >  
> > >  	dw_pcie_edma_remove(pci);
> > >  
> > > +	if (pp->msg_res) {
> > > +		release_resource(pp->msg_res);
> > > +		devm_kfree(pci->dev, pp->msg_res);
> > > +	}
> > > +
> > >  	if (pp->has_msi_ctrl)
> > >  		dw_pcie_free_msi(pp);
> > >  
> > > @@ -702,6 +742,10 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> > >  		atu.pci_addr = entry->res->start - entry->offset;
> > >  		atu.size = resource_size(entry->res);
> > >  
> > > +		/* MSG TLB window resource reserve at one of end of IORESOURCE_MEM resource */
> > 
> > How about,
> > 
> > 		/* Adjust iATU size if MSG TLP region was allocated before */
> > 		if (pp->msg_res && pp->msg_res->parent == entry->res)
> > 			atu.size = resource_size(entry->res) -
> > 					resource_size(pp->msg_res);
> > 		else
> > 			atu.size = resource_size(entry->res);
> > 
> > > +		if (pp->msg_res && pp->msg_res->parent == entry->res)
> > > +			atu.size -= resource_size(pp->msg_res);
> > > +
> > >  		ret = dw_pcie_prog_outbound_atu(pci, &atu);
> > >  		if (ret) {
> > >  			dev_err(pci->dev, "Failed to set MEM range %pr\n",
> > > @@ -733,6 +777,8 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> > >  		dev_warn(pci->dev, "Ranges exceed outbound iATU size (%d)\n",
> > >  			 pci->num_ob_windows);
> > >  
> > > +	pp->msg_atu_index = i;
> > > +
> > >  	i = 0;
> > >  	resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {
> > >  		if (resource_type(entry->res) != IORESOURCE_MEM)
> > > @@ -838,11 +884,48 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
> > >  }
> > >  EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
> > >  
> > > +/* Using message outbound ATU to send out PME_Turn_Off message for dwc PCIe controller */
> > 
> > No need of this comment.
> > 
> > > +static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
> > > +{
> > > +	struct dw_pcie_ob_atu_cfg atu = { 0 };
> > > +	void __iomem *mem;
> > > +	int ret;
> > > +
> > > +	if (pci->num_ob_windows <= pci->pp.msg_atu_index)
> > > +		return -EINVAL;
> > 
> > 		return -ENOSPC;
> > 
> > > +
> > > +	if (!pci->pp.msg_res)
> > > +		return -EINVAL;
> > 
> > 		return -ENOSPC;
> > - Mani
> > 
> > -- 
> > மணிவண்ணன் சதாசிவம்

-- 
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