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authorSerge Semin <Sergey.Semin@baikalelectronics.ru>2022-09-09 22:36:08 +0300
committerDamien Le Moal <damien.lemoal@opensource.wdc.com>2022-09-17 01:39:34 +0900
commitf67f12ff57bcfcd7d64280f748787793217faeaf (patch)
tree3514925a9eef7ed8b16e579a40c90dba044ff384 /drivers/ata
parentata: libahci_platform: Parse ports-implemented property in resources getter (diff)
downloadlinux-dev-f67f12ff57bcfcd7d64280f748787793217faeaf.tar.xz
linux-dev-f67f12ff57bcfcd7d64280f748787793217faeaf.zip
ata: libahci_platform: Introduce reset assertion/deassertion methods
Currently the ACHI-platform library supports only the assert and deassert reset signals and ignores the platforms with self-deasserting reset lines. That prone to having the platforms with self-deasserting reset method misbehaviour when it comes to resuming from sleep state after the clocks have been fully disabled. For such cases the controller needs to be fully reset all over after the reference clocks are enabled and stable, otherwise the controller state machine might be in an undetermined state. The best solution would be to auto-detect which reset method is supported by the particular platform and use it implicitly in the framework of the ahci_platform_enable_resources()/ahci_platform_disable_resources() methods. Alas it can't be implemented due to the AHCI-platform library already supporting the shared reset control lines. As [1] says in such case we have to use only one of the next methods: + reset_control_assert()/reset_control_deassert(); + reset_control_reset()/reset_control_rearm(). If the driver had an exclusive control over the reset lines we could have been able to manipulate the lines with no much limitation and just used the combination of the methods above to cover all the possible reset-control cases. Since the shared reset control has already been advertised and couldn't be changed with no risk to breaking the platforms relying on it, we have no choice but to make the platform drivers to determine which reset methods the platform reset system supports. In order to implement both types of reset control support we suggest to introduce the new AHCI-platform flag: AHCI_PLATFORM_RST_TRIGGER, which when passed to the ahci_platform_get_resources() method together with the AHCI_PLATFORM_GET_RESETS flag will indicate that the reset lines are self-deasserting thus the reset_control_reset()/reset_control_rearm() will be used to control the reset state. Otherwise the reset_control_deassert()/reset_control_assert() methods will be utilized. [1] Documentation/driver-api/reset.rst Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Diffstat (limited to 'drivers/ata')
-rw-r--r--drivers/ata/ahci.h1
-rw-r--r--drivers/ata/libahci_platform.c50
2 files changed, 46 insertions, 5 deletions
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index c3770a19781b..7d834deefeb9 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -340,6 +340,7 @@ struct ahci_host_priv {
bool got_runtime_pm; /* Did we do pm_runtime_get? */
unsigned int n_clks;
struct clk_bulk_data *clks; /* Optional */
+ unsigned int f_rsts;
struct reset_control *rsts; /* Optional */
struct regulator **target_pwrs; /* Optional */
struct regulator *ahci_regulator;/* Optional */
diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
index 085f99b2eb5a..31be8a10facd 100644
--- a/drivers/ata/libahci_platform.c
+++ b/drivers/ata/libahci_platform.c
@@ -123,6 +123,44 @@ void ahci_platform_disable_clks(struct ahci_host_priv *hpriv)
EXPORT_SYMBOL_GPL(ahci_platform_disable_clks);
/**
+ * ahci_platform_deassert_rsts - Deassert/trigger platform resets
+ * @hpriv: host private area to store config values
+ *
+ * This function deasserts or triggers all the reset lines found for
+ * the AHCI device.
+ *
+ * RETURNS:
+ * 0 on success otherwise a negative error code
+ */
+int ahci_platform_deassert_rsts(struct ahci_host_priv *hpriv)
+{
+ if (hpriv->f_rsts & AHCI_PLATFORM_RST_TRIGGER)
+ return reset_control_reset(hpriv->rsts);
+
+ return reset_control_deassert(hpriv->rsts);
+}
+EXPORT_SYMBOL_GPL(ahci_platform_deassert_rsts);
+
+/**
+ * ahci_platform_assert_rsts - Assert/rearm platform resets
+ * @hpriv: host private area to store config values
+ *
+ * This function asserts or rearms (for self-deasserting resets) all
+ * the reset controls found for the AHCI device.
+ *
+ * RETURNS:
+ * 0 on success otherwise a negative error code
+ */
+int ahci_platform_assert_rsts(struct ahci_host_priv *hpriv)
+{
+ if (hpriv->f_rsts & AHCI_PLATFORM_RST_TRIGGER)
+ return reset_control_rearm(hpriv->rsts);
+
+ return reset_control_assert(hpriv->rsts);
+}
+EXPORT_SYMBOL_GPL(ahci_platform_assert_rsts);
+
+/**
* ahci_platform_enable_regulators - Enable regulators
* @hpriv: host private area to store config values
*
@@ -219,18 +257,18 @@ int ahci_platform_enable_resources(struct ahci_host_priv *hpriv)
if (rc)
goto disable_regulator;
- rc = reset_control_deassert(hpriv->rsts);
+ rc = ahci_platform_deassert_rsts(hpriv);
if (rc)
goto disable_clks;
rc = ahci_platform_enable_phys(hpriv);
if (rc)
- goto disable_resets;
+ goto disable_rsts;
return 0;
-disable_resets:
- reset_control_assert(hpriv->rsts);
+disable_rsts:
+ ahci_platform_assert_rsts(hpriv);
disable_clks:
ahci_platform_disable_clks(hpriv);
@@ -257,7 +295,7 @@ void ahci_platform_disable_resources(struct ahci_host_priv *hpriv)
{
ahci_platform_disable_phys(hpriv);
- reset_control_assert(hpriv->rsts);
+ ahci_platform_assert_rsts(hpriv);
ahci_platform_disable_clks(hpriv);
@@ -448,6 +486,8 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
rc = PTR_ERR(hpriv->rsts);
goto err_out;
}
+
+ hpriv->f_rsts = flags & AHCI_PLATFORM_RST_TRIGGER;
}
/*