Re: [PATCH v4 16/23] ata: ahci: Introduce firmware-specific caps initialization

Serge Semin
2022-06-15T21:11:44Z

On Tue, Jun 14, 2022 at 05:42:35PM +0900, Damien Le Moal wrote:
> On 6/10/22 17:17, Serge Semin wrote:
> > There are systems with no BIOS or comprehensive embedded firmware which
> > could be able to properly initialize the SATA AHCI controller
> > platform-specific capabilities. In that case a good alternative to having
> > a clever bootloader is to create a device tree node with the properties
> > well describing all the AHCI-related platform specifics. All the settings
> > which are normally detected and marked as available in the HBA and its
> > ports capabilities fields [1] could be defined in the platform DTB by
> > means of a set of the dedicated properties. Such approach perfectly fits
> > to the DTB-philosophy - to provide hardware/platform description.
> >
> > So here we suggest to extend the SATA AHCI device tree bindings with two
> > additional DT-properties:
> > 1) "hba-cap" - HBA platform generic capabilities like:
> > - SSS - Staggered Spin-up support.
> > - SMPS - Mechanical Presence Switch support.
> > 2) "hba-port-cap" - HBA platform port capabilities like:
> > - HPCP - Hot Plug Capable Port.
> > - MPSP - Mechanical Presence Switch Attached to Port.
> > - CPD - Cold Presence Detection.
> > - ESP - External SATA Port.
> > - FBSCP - FIS-based Switching Capable Port.
> > All of these capabilities require to have a corresponding hardware
> > configuration. Thus it's ok to have them defined in DTB.
> >
> > Even though the driver currently takes into account the state of the ESP
> > and FBSCP flags state only, there is nothing wrong with having all of them
> > supported by the generic AHCI library in order to have a complete OF-based
> > platform-capabilities initialization procedure. These properties will be
> > parsed in the ahci_platform_get_resources() method and their values will
> > be stored in the saved_* fields of the ahci_host_priv structure, which in
> > its turn then will be used to restore the H.CAP, H.PI and P#.CMD
> > capability fields on device init and after HBA reset.
> >
> > Please note this modification concerns the HW-init HBA and its ports flags
> > only, which are by specification [1] are supposed to be initialized by the
> > BIOS/platform firmware/expansion ROM and which are normally declared in
> > the one-time-writable-after-reset register fields. Even though these flags
> > aren't supposed to be cleared after HBA reset some AHCI instances may
> > violate that rule so we still need to perform the fields resetting after
> > each reset. Luckily the corresponding functionality has already been
> > partly implemented in the framework of the ahci_save_initial_config() and
> > ahci_restore_initial_config() methods.
> >
> > [1] Serial ATA AHCI 1.3.1 Specification, p. 103
> >
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> >
> > ---
> >
> > Changelog v4:
> > - Convert the boolean properties to the bitfield DT-properties. (@Rob)
> > ---
> > drivers/ata/ahci.h | 1 +
> > drivers/ata/libahci.c | 51 ++++++++++++++++++++++++++++------
> > drivers/ata/libahci_platform.c | 41 +++++++++++++++++++++++++--
> > 3 files changed, 82 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
> > index 8b9826533ae5..0de221055961 100644
> > --- a/drivers/ata/ahci.h
> > +++ b/drivers/ata/ahci.h
> > @@ -337,6 +337,7 @@ struct ahci_host_priv {
> > u32 saved_cap; /* saved initial cap */
> > u32 saved_cap2; /* saved initial cap2 */
> > u32 saved_port_map; /* saved initial port_map */
> > + u32 saved_port_cap[AHCI_MAX_PORTS]; /* saved port_cap */
> > u32 em_loc; /* enclosure management location */
> > u32 em_buf_sz; /* EM buffer size in byte */
> > u32 em_msg_type; /* EM message type */
> > diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> > index 1ffaa5f5f21a..954386a2b500 100644
> > --- a/drivers/ata/libahci.c
> > +++ b/drivers/ata/libahci.c
> > @@ -16,6 +16,7 @@
> > * http://www.intel.com/technology/serialata/pdf/rev1_1.pdf
> > */
> >
> > +#include <linux/bitops.h>
> > #include <linux/kernel.h>
> > #include <linux/gfp.h>
> > #include <linux/module.h>
> > @@ -443,16 +444,28 @@ static ssize_t ahci_show_em_supported(struct device *dev,
> > void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
> > {
> > void __iomem *mmio = hpriv->mmio;
> > - u32 cap, cap2, vers, port_map;
> > + void __iomem *port_mmio;
> > + unsigned long port_map;
> > + u32 cap, cap2, vers;
> > int i;
> >
> > /* make sure AHCI mode is enabled before accessing CAP */
> > ahci_enable_ahci(mmio);
> >
> > - /* Values prefixed with saved_ are written back to host after
> > - * reset. Values without are used for driver operation.
> > + /*
> > + * Values prefixed with saved_ are written back to the HBA and ports
> > + * registers after reset. Values without are used for driver operation.
> > + */
> > +
> > + /*
> > + * Override HW-init HBA capability fields with the platform-specific
> > + * values. The rest of the HBA capabilities are defined as Read-only
> > + * and can't be modified in CSR anyway.
> > */
> > - hpriv->saved_cap = cap = readl(mmio + HOST_CAP);
> > + cap = readl(mmio + HOST_CAP);
> > + if (hpriv->saved_cap)
> > + cap = (cap & ~(HOST_CAP_SSS | HOST_CAP_MPS)) | hpriv->saved_cap;
> > + hpriv->saved_cap = cap;
> >
> > /* CAP2 register is only defined for AHCI 1.2 and later */
> > vers = readl(mmio + HOST_VERSION);
> > @@ -519,7 +532,7 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
> > /* Override the HBA ports mapping if the platform needs it */
> > port_map = readl(mmio + HOST_PORTS_IMPL);
> > if (hpriv->saved_port_map && port_map != hpriv->saved_port_map) {
> > - dev_info(dev, "forcing port_map 0x%x -> 0x%x\n",
> > + dev_info(dev, "forcing port_map 0x%lx -> 0x%x\n",
>

> This change is not necessary.

It is. The port_map type has been changed.

>
> > port_map, hpriv->saved_port_map);
> > port_map = hpriv->saved_port_map;
> > } else {
> > @@ -527,7 +540,7 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
> > }
> >
> > if (hpriv->mask_port_map) {
> > - dev_warn(dev, "masking port_map 0x%x -> 0x%x\n",
> > + dev_warn(dev, "masking port_map 0x%lx -> 0x%lx\n",
>
> Same.

ditto

>
> > port_map,
> > port_map & hpriv->mask_port_map);
> > port_map &= hpriv->mask_port_map;
> > @@ -546,7 +559,7 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
> > */
> > if (map_ports > ahci_nr_ports(cap)) {
> > dev_warn(dev,
> > - "implemented port map (0x%x) contains more ports than nr_ports (%u), using nr_ports\n",
> > + "implemented port map (0x%lx) contains more ports than nr_ports (%u), using nr_ports\n",
>
> Same.

ditto.

>
> > port_map, ahci_nr_ports(cap));
> > port_map = 0;
> > }
> > @@ -555,12 +568,26 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
> > /* fabricate port_map from cap.nr_ports for < AHCI 1.3 */
> > if (!port_map && vers < 0x10300) {
> > port_map = (1 << ahci_nr_ports(cap)) - 1;
> > - dev_warn(dev, "forcing PORTS_IMPL to 0x%x\n", port_map);
> > + dev_warn(dev, "forcing PORTS_IMPL to 0x%lx\n", port_map);
>
> And again not needed.

and ditto.

>
> >
> > /* write the fixed up value to the PI register */
> > hpriv->saved_port_map = port_map;
> > }
> >
> > + /*
> > + * Preserve the ports capabilities defined by the platform. Note there
> > + * is no need in storing the rest of the P#.CMD fields since they are
> > + * volatile.
> > + */
> > + for_each_set_bit(i, &port_map, AHCI_MAX_PORTS) {
> > + if (hpriv->saved_port_cap[i])
> > + continue;
> > +
> > + port_mmio = __ahci_port_base(hpriv, i);
> > + hpriv->saved_port_cap[i] =
> > + readl(port_mmio + PORT_CMD) & PORT_CMD_CAP;
> > + }
> > +
> > /* record values to use during operation */
> > hpriv->cap = cap;
> > hpriv->cap2 = cap2;
> > @@ -590,13 +617,21 @@ EXPORT_SYMBOL_GPL(ahci_save_initial_config);
> > static void ahci_restore_initial_config(struct ata_host *host)
> > {
> > struct ahci_host_priv *hpriv = host->private_data;
> > + unsigned long port_map = hpriv->port_map;
> > void __iomem *mmio = hpriv->mmio;
> > + void __iomem *port_mmio;
> > + int i;
> >
> > writel(hpriv->saved_cap, mmio + HOST_CAP);
> > if (hpriv->saved_cap2)
> > writel(hpriv->saved_cap2, mmio + HOST_CAP2);
> > writel(hpriv->saved_port_map, mmio + HOST_PORTS_IMPL);
> > (void) readl(mmio + HOST_PORTS_IMPL); /* flush */
> > +
> > + for_each_set_bit(i, &port_map, AHCI_MAX_PORTS) {
> > + port_mmio = __ahci_port_base(hpriv, i);
> > + writel(hpriv->saved_port_cap[i], port_mmio + PORT_CMD);
> > + }
> > }
> >
> > static unsigned ahci_scr_offset(struct ata_port *ap, unsigned int sc_reg)
> > diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
> > index efe640603f3f..8b542a8bc487 100644
> > --- a/drivers/ata/libahci_platform.c
> > +++ b/drivers/ata/libahci_platform.c
> > @@ -23,6 +23,7 @@
> > #include <linux/pm_runtime.h>
> > #include <linux/of_platform.h>
> > #include <linux/reset.h>
> > +
>
> white line change.

Ok. I'll drop it.

-Sergey

>
> > #include "ahci.h"
> >
> > static void ahci_host_stop(struct ata_host *host);
> > @@ -383,6 +384,34 @@ static int ahci_platform_get_regulator(struct ahci_host_priv *hpriv, u32 port,
> > return rc;
> > }
> >
> > +static int ahci_platform_get_firmware(struct ahci_host_priv *hpriv,
> > + struct device *dev)
> > +{
> > + struct device_node *child;
> > + u32 port;
> > +
> > + if (!of_property_read_u32(dev->of_node, "hba-cap", &hpriv->saved_cap))
> > + hpriv->saved_cap &= (HOST_CAP_SSS | HOST_CAP_MPS);
> > +
> > + of_property_read_u32(dev->of_node,
> > + "ports-implemented", &hpriv->saved_port_map);
> > +
> > + for_each_child_of_node(dev->of_node, child) {
> > + if (!of_device_is_available(child))
> > + continue;
> > +
> > + if (of_property_read_u32(child, "reg", &port)) {
> > + of_node_put(child);
> > + return -EINVAL;
> > + }
> > +
> > + if (!of_property_read_u32(child, "hba-port-cap", &hpriv->saved_port_cap[port]))
> > + hpriv->saved_port_cap[port] &= PORT_CMD_CAP;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > /**
> > * ahci_platform_get_resources - Get platform resources
> > * @pdev: platform device to get resources for
> > @@ -523,9 +552,6 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
> > goto err_out;
> > }
> >
> > - of_property_read_u32(dev->of_node,
> > - "ports-implemented", &hpriv->saved_port_map);
> > -
> > if (child_nodes) {
> > for_each_child_of_node(dev->of_node, child) {
> > u32 port;
> > @@ -590,6 +616,15 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
> > if (rc == -EPROBE_DEFER)
> > goto err_out;
> > }
> > +
> > + /*
> > + * Retrieve firmware-specific flags which then will be used to set
> > + * the HW-init fields of HBA and its ports
> > + */
> > + rc = ahci_platform_get_firmware(hpriv, dev);
> > + if (rc)
> > + goto err_out;
> > +
> > pm_runtime_enable(dev);
> > pm_runtime_get_sync(dev);
> > hpriv->got_runtime_pm = true;
>
>
> --
> Damien Le Moal
> Western Digital Research