linux-kernel - Re: [PATCH v11 14/20] cxl/pci: Map RCH downstream AER registers for logging protocol errors

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Date:   Mon, 2 Oct 2023 15:56:58 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Robert Richter <rrichter@....com>
CC:     Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        "Davidlohr Bueso" <dave@...olabs.net>,
        Dave Jiang <dave.jiang@...el.com>, <linux-cxl@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Terry Bowman <terry.bowman@....com>
Subject: Re: [PATCH v11 14/20] cxl/pci: Map RCH downstream AER registers for
 logging protocol errors

On Wed, 27 Sep 2023 17:43:33 +0200
Robert Richter <rrichter@....com> wrote:

> From: Terry Bowman <terry.bowman@....com>
> 
> The restricted CXL host (RCH) error handler will log protocol errors
> using AER and RAS status registers. The AER and RAS registers need to
> be virtually memory mapped before enabling interrupts. Create the
> initializer function devm_cxl_setup_parent_dport() for this when the
> endpoint is connected with the dport. The initialization sets up the
> RCH RAS and AER mappings.
> 
> Add 'struct cxl_regs' to 'struct cxl_dport' for saving a pointer to
> the RCH downstream port's AER and RAS registers.
> 
> Co-developed-by: Robert Richter <rrichter@....com>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
As before. Co-dev just before SoB. 

https://elixir.bootlin.com/linux/latest/source/Documentation/process/submitting-patches.rst#L521
This example looks like what you have here.

> Signed-off-by: Robert Richter <rrichter@....com>
Otherwise, LGTM

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

> ---
>  drivers/cxl/core/pci.c | 36 ++++++++++++++++++++++++++++++++++++
>  drivers/cxl/cxl.h      | 10 ++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 2b8883288539..2af7ad77b273 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -5,6 +5,7 @@
>  #include <linux/delay.h>
>  #include <linux/pci.h>
>  #include <linux/pci-doe.h>
> +#include <linux/aer.h>
>  #include <cxlpci.h>
>  #include <cxlmem.h>
>  #include <cxl.h>
> @@ -730,6 +731,38 @@ static bool cxl_handle_endpoint_ras(struct cxl_dev_state *cxlds)
>  
>  #ifdef CONFIG_PCIEAER_CXL
>  
> +static void cxl_dport_map_rch_aer(struct cxl_dport *dport)
> +{
> +	struct cxl_rcrb_info *ri = &dport->rcrb;
> +	void __iomem *dport_aer = NULL;
> +	resource_size_t aer_phys;
> +	struct device *host;
> +
> +	if (dport->rch && ri->aer_cap) {
> +		host = dport->reg_map.host;
> +		aer_phys = ri->aer_cap + ri->base;
> +		dport_aer = devm_cxl_iomap_block(host, aer_phys,
> +				sizeof(struct aer_capability_regs));
> +	}
> +
> +	dport->regs.dport_aer = dport_aer;
> +}
> +
> +static void cxl_dport_map_regs(struct cxl_dport *dport)
> +{
> +	struct cxl_register_map *map = &dport->reg_map;
> +	struct device *dev = dport->dport_dev;
> +
> +	if (!map->component_map.ras.valid)
> +		dev_dbg(dev, "RAS registers not found\n");
> +	else if (cxl_map_component_regs(map, &dport->regs.component,
> +					BIT(CXL_CM_CAP_CAP_ID_RAS)))
> +		dev_dbg(dev, "Failed to map RAS capability.\n");
> +
> +	if (dport->rch)
> +		cxl_dport_map_rch_aer(dport);
> +}
> +
>  void devm_cxl_setup_parent_dport(struct device *host, struct cxl_dport *dport)
>  {
>  	struct device *dport_dev = dport->dport_dev;
> @@ -738,6 +771,9 @@ void devm_cxl_setup_parent_dport(struct device *host, struct cxl_dport *dport)
>  	host_bridge = to_pci_host_bridge(dport_dev);
>  	if (host_bridge->native_cxl_error)
>  		dport->rcrb.aer_cap = cxl_rcrb_to_aer(dport_dev, dport->rcrb.base);
> +
> +	dport->reg_map.host = host;
> +	cxl_dport_map_regs(dport);
>  }
>  EXPORT_SYMBOL_NS_GPL(devm_cxl_setup_parent_dport, CXL);
>  
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index cfa2f6bede41..7c2c195592d6 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -221,6 +221,14 @@ struct cxl_regs {
>  	struct_group_tagged(cxl_pmu_regs, pmu_regs,
>  		void __iomem *pmu;
>  	);
> +
> +	/*
> +	 * RCH downstream port specific RAS register
> +	 * @aer: CXL 3.0 8.2.1.1 RCH Downstream Port RCRB
> +	 */
> +	struct_group_tagged(cxl_rch_regs, rch_regs,
> +		void __iomem *dport_aer;
> +	);
>  };
>  
>  struct cxl_reg_map {
> @@ -623,6 +631,7 @@ struct cxl_rcrb_info {
>   * @rcrb: Data about the Root Complex Register Block layout
>   * @rch: Indicate whether this dport was enumerated in RCH or VH mode
>   * @port: reference to cxl_port that contains this downstream port
> + * @regs: Dport parsed register blocks
>   */
>  struct cxl_dport {
>  	struct device *dport_dev;
> @@ -631,6 +640,7 @@ struct cxl_dport {
>  	struct cxl_rcrb_info rcrb;
>  	bool rch;
>  	struct cxl_port *port;
> +	struct cxl_regs regs;
>  };
>  
>  /**