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

Damien Le Moal
2022-06-16T00:30:07Z

On 2022/06/16 6:11, Serge Semin wrote:
> 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.

Ignore. When I read the patches the other day, the mailer font had that "l" look
like a "1" :) My mistake.

>
>>
>>> 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

--
Damien Le Moal
Western Digital Research