Synopsys AHCI SATA controller can work pretty under with the generic
AHCI-platform driver control. But there are vendor-specific peculiarities
which can tune the device performance up and which may need to be fixed up
for proper device functioning. In addition some DWC AHCI-based controllers
may require small platform-specific fixups, so adding them in the generic
AHCI driver would have ruined the code simplicity. Shortly speaking in
order to keep the generic AHCI-platform code clean and have DWC AHCI
SATA-specific features supported we suggest to add a dedicated DWC AHCI
SATA device driver. Aside with the standard AHCI-platform resources
getting, enabling/disabling and the controller registration the new driver
performs the next actions.
First of all there is a way to verify whether the HBA/ports capabilities
activated in OF are correct. Almost all features availability is reflected
in the vendor-specific parameters registers. So the DWC AHCI driver does
the capabilities sanity check based on the corresponding fields state.
Secondly if either the Command Completion Coalescing or the Device Sleep
feature is enabled the DWC AHCI-specific internal 1ms timer must be fixed
in accordance with the application clock signal frequency. In particular
the timer value must be set to be Fapp * 1000. Normally the SoC designers
pre-configure the TIMER1MS register to contain a correct value by default.
But the platforms can support the application clock rate change. If that
happens the 1ms timer value must be accordingly updated otherwise the
dependent features won't work as expected. In the DWC AHCI driver we
suggest to rely on the "aclk" reference clock rate to set the timer
interval up. That clock source is supposed to be the AHCI SATA application
clock in accordance with the DT bindings.
Finally DWC AHCI SATA controller AXI/AHB bus DMA-engine can be tuned up to
transfer up to 1024 * FIFO words at a time by setting the Tx/Rx
transaction size in the DMA control register. The maximum value depends on
the DMA data bus and AXI/AHB bus maximum burst length. In most of the
cases it's better to set the maximum possible value to reach the best AHCI
SATA controller performance. But sometimes in order to improve the system
interconnect responsiveness, transferring in smaller data chunks may be
more preferable. For such cases and for the case when the default value
doesn't provide the best DMA bus performance we suggest to use the new
HBA-port specific DT-properties "snps,{tx,rx}-ts-max" to tune the DMA
transactions size up.
After all the settings denoted above are handled the DWC AHCI SATA driver
proceeds further with the standard AHCI-platform host initializations.
Note since DWC AHCI controller is now have a dedicated driver we can
discard the corresponding compatible string from the ahci-platform.c
module. The same concerns "snps,spear-ahci" compatible string, which is
also based on the DWC AHCI IP-core.
Signed-off-by: Serge Semin <[email protected]>
---
Note there are three more AHCI SATA drivers which have been created for
the devices based on the DWC AHCI SATA IP-core. It's AHCI SunXi, St and
iMX drivers. Mostly they don't support the features implemented in this
driver. So hopefully sometime in future they can be converted to be based
on the generic DWC AHCI SATA driver and just perform some
subvendor-specific setups in their own LLDD (glue) driver code. But for
now let's leave the generic DWC AHCI SATA code as is. Hopefully the new
DWC AHCI-based device drivers will try at least to re-use a part of the
DWC AHCI driver methods if not being able to be integrated in the generic
DWC driver code.
Changelog v2:
- Change the local objects prefix from 'dwc_ahci_' to 'ahci_dwc_'.
(@Damien)
---
drivers/ata/Kconfig | 10 +
drivers/ata/Makefile | 1 +
drivers/ata/ahci_dwc.c | 395 ++++++++++++++++++++++++++++++++++++
drivers/ata/ahci_platform.c | 2 -
4 files changed, 406 insertions(+), 2 deletions(-)
create mode 100644 drivers/ata/ahci_dwc.c
diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index bb45a9c00514..95e0e022b5bb 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -176,6 +176,16 @@ config AHCI_DM816
If unsure, say N.
+config AHCI_DWC
+ tristate "Synopsys DWC AHCI SATA support"
+ select SATA_HOST
+ default SATA_AHCI_PLATFORM
+ help
+ This option enables support for the Synopsys DWC AHCI SATA
+ controller implementation.
+
+ If unsure, say N.
+
config AHCI_ST
tristate "ST AHCI SATA support"
depends on ARCH_STI
diff --git a/drivers/ata/Makefile b/drivers/ata/Makefile
index b8aebfb14e82..34623365d9a6 100644
--- a/drivers/ata/Makefile
+++ b/drivers/ata/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_AHCI_BRCM) += ahci_brcm.o libahci.o libahci_platform.o
obj-$(CONFIG_AHCI_CEVA) += ahci_ceva.o libahci.o libahci_platform.o
obj-$(CONFIG_AHCI_DA850) += ahci_da850.o libahci.o libahci_platform.o
obj-$(CONFIG_AHCI_DM816) += ahci_dm816.o libahci.o libahci_platform.o
+obj-$(CONFIG_AHCI_DWC) += ahci_dwc.o libahci.o libahci_platform.o
obj-$(CONFIG_AHCI_IMX) += ahci_imx.o libahci.o libahci_platform.o
obj-$(CONFIG_AHCI_MTK) += ahci_mtk.o libahci.o libahci_platform.o
obj-$(CONFIG_AHCI_MVEBU) += ahci_mvebu.o libahci.o libahci_platform.o
diff --git a/drivers/ata/ahci_dwc.c b/drivers/ata/ahci_dwc.c
new file mode 100644
index 000000000000..73380aaaebab
--- /dev/null
+++ b/drivers/ata/ahci_dwc.c
@@ -0,0 +1,395 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * DWC AHCI SATA Platform driver
+ *
+ * Copyright (C) 2021 BAIKAL ELECTRONICS, JSC
+ */
+
+#include <linux/ahci_platform.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/libata.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+
+#include "ahci.h"
+
+#define DRV_NAME "ahci-dwc"
+
+#define AHCI_DWC_FBS_PMPN_MAX 15
+
+/* DWC AHCI SATA controller specific registers */
+#define AHCI_DWC_HOST_OOBR 0xbc
+#define AHCI_DWC_HOST_OOB_WE BIT(31)
+#define AHCI_DWC_HOST_CWMIN_MASK GENMASK(30, 24)
+#define AHCI_DWC_HOST_CWMAX_MASK GENMASK(23, 16)
+#define AHCI_DWC_HOST_CIMIN_MASK GENMASK(15, 8)
+#define AHCI_DWC_HOST_CIMAX_MASK GENMASK(7, 0)
+
+#define AHCI_DWC_HOST_GPCR 0xd0
+#define AHCI_DWC_HOST_GPSR 0xd4
+
+#define AHCI_DWC_HOST_TIMER1MS 0xe0
+#define AHCI_DWC_HOST_TIMV_MASK GENMASK(19, 0)
+
+#define AHCI_DWC_HOST_GPARAM1R 0xe8
+#define AHCI_DWC_HOST_ALIGN_M BIT(31)
+#define AHCI_DWC_HOST_RX_BUFFER BIT(30)
+#define AHCI_DWC_HOST_PHY_DATA_MASK GENMASK(29, 28)
+#define AHCI_DWC_HOST_PHY_RST BIT(27)
+#define AHCI_DWC_HOST_PHY_CTRL_MASK GENMASK(26, 21)
+#define AHCI_DWC_HOST_PHY_STAT_MASK GENMASK(20, 15)
+#define AHCI_DWC_HOST_LATCH_M BIT(14)
+#define AHCI_DWC_HOST_PHY_TYPE_MASK GENMASK(13, 11)
+#define AHCI_DWC_HOST_RET_ERR BIT(10)
+#define AHCI_DWC_HOST_AHB_ENDIAN_MASK GENMASK(9, 8)
+#define AHCI_DWC_HOST_S_HADDR BIT(7)
+#define AHCI_DWC_HOST_M_HADDR BIT(6)
+#define AHCI_DWC_HOST_S_HDATA_MASK GENMASK(5, 3)
+#define AHCI_DWC_HOST_M_HDATA_MASK GENMASK(2, 0)
+
+#define AHCI_DWC_HOST_GPARAM2R 0xec
+#define AHCI_DWC_HOST_FBS_MEM_S BIT(19)
+#define AHCI_DWC_HOST_FBS_PMPN_MASK GENMASK(17, 16)
+#define AHCI_DWC_HOST_FBS_SUP BIT(15)
+#define AHCI_DWC_HOST_DEV_CP BIT(14)
+#define AHCI_DWC_HOST_DEV_MP BIT(13)
+#define AHCI_DWC_HOST_ENCODE_M BIT(12)
+#define AHCI_DWC_HOST_RXOOB_CLK_M BIT(11)
+#define AHCI_DWC_HOST_RXOOB_M BIT(10)
+#define AHCI_DWC_HOST_TXOOB_M BIT(9)
+#define AHCI_DWC_HOST_RXOOB_M BIT(10)
+#define AHCI_DWC_HOST_RXOOB_CLK_MASK GENMASK(8, 0)
+
+#define AHCI_DWC_HOST_PPARAMR 0xf0
+#define AHCI_DWC_HOST_TX_MEM_M BIT(11)
+#define AHCI_DWC_HOST_TX_MEM_S BIT(10)
+#define AHCI_DWC_HOST_RX_MEM_M BIT(9)
+#define AHCI_DWC_HOST_RX_MEM_S BIT(8)
+#define AHCI_DWC_HOST_TXFIFO_DEPTH GENMASK(7, 4)
+#define AHCI_DWC_HOST_RXFIFO_DEPTH GENMASK(3, 0)
+
+#define AHCI_DWC_HOST_TESTR 0xf4
+#define AHCI_DWC_HOST_PSEL_MASK GENMASK(18, 16)
+#define AHCI_DWC_HOST_TEST_IF BIT(0)
+
+#define AHCI_DWC_HOST_VERSIONR 0xf8
+#define AHCI_DWC_HOST_IDR 0xfc
+
+#define AHCI_DWC_PORT_DMACR 0x70
+#define AHCI_DWC_PORT_RXABL_MASK GENMASK(15, 12)
+#define AHCI_DWC_PORT_TXABL_MASK GENMASK(11, 8)
+#define AHCI_DWC_PORT_RXTS_MASK GENMASK(7, 4)
+#define AHCI_DWC_PORT_TXTS_MASK GENMASK(3, 0)
+#define AHCI_DWC_PORT_PHYCR 0x74
+#define AHCI_DWC_PORT_PHYSR 0x78
+
+struct ahci_dwc_host_priv {
+ struct platform_device *pdev;
+
+ u32 timv;
+ u32 dmacr[AHCI_MAX_PORTS];
+};
+
+static struct ahci_host_priv *ahci_dwc_get_resources(struct platform_device *pdev)
+{
+ struct ahci_dwc_host_priv *dpriv;
+ struct ahci_host_priv *hpriv;
+
+ dpriv = devm_kzalloc(&pdev->dev, sizeof(*dpriv), GFP_KERNEL);
+ if (!dpriv)
+ return ERR_PTR(-ENOMEM);
+
+ dpriv->pdev = pdev;
+
+ hpriv = ahci_platform_get_resources(pdev, AHCI_PLATFORM_GET_RESETS);
+ if (IS_ERR(hpriv))
+ return hpriv;
+
+ hpriv->plat_data = (void *)dpriv;
+
+ return hpriv;
+}
+
+static void ahci_dwc_check_cap(struct ahci_host_priv *hpriv)
+{
+ unsigned long port_map = hpriv->saved_port_map | hpriv->mask_port_map;
+ struct ahci_dwc_host_priv *dpriv = hpriv->plat_data;
+ bool dev_mp, dev_cp, fbs_sup;
+ unsigned int fbs_pmp;
+ u32 param;
+ int i;
+
+ param = readl(hpriv->mmio + AHCI_DWC_HOST_GPARAM2R);
+ dev_mp = !!(param & AHCI_DWC_HOST_DEV_MP);
+ dev_cp = !!(param & AHCI_DWC_HOST_DEV_CP);
+ fbs_sup = !!(param & AHCI_DWC_HOST_FBS_SUP);
+ fbs_pmp = 5 * FIELD_GET(AHCI_DWC_HOST_FBS_PMPN_MASK, param);
+
+ if (!dev_mp && hpriv->saved_cap & HOST_CAP_MPS) {
+ dev_warn(&dpriv->pdev->dev, "MPS is unsupported\n");
+ hpriv->saved_cap &= ~HOST_CAP_MPS;
+ }
+
+
+ if (fbs_sup && fbs_pmp < AHCI_DWC_FBS_PMPN_MAX) {
+ dev_warn(&dpriv->pdev->dev, "PMPn is limited up to %u ports\n",
+ fbs_pmp);
+ }
+
+ for_each_set_bit(i, &port_map, AHCI_MAX_PORTS) {
+ if (!dev_mp && hpriv->saved_port_cap[i] & PORT_CMD_MPSP) {
+ dev_warn(&dpriv->pdev->dev, "MPS incapable port %d\n", i);
+ hpriv->saved_port_cap[i] &= ~PORT_CMD_MPSP;
+ }
+
+ if (!dev_cp && hpriv->saved_port_cap[i] & PORT_CMD_CPD) {
+ dev_warn(&dpriv->pdev->dev, "CPD incapable port %d\n", i);
+ hpriv->saved_port_cap[i] &= ~PORT_CMD_CPD;
+ }
+
+ if (!fbs_sup && hpriv->saved_port_cap[i] & PORT_CMD_FBSCP) {
+ dev_warn(&dpriv->pdev->dev, "FBS incapable port %d\n", i);
+ hpriv->saved_port_cap[i] &= ~PORT_CMD_FBSCP;
+ }
+ }
+}
+
+static void ahci_dwc_init_timer(struct ahci_host_priv *hpriv)
+{
+ struct ahci_dwc_host_priv *dpriv = hpriv->plat_data;
+ unsigned long rate;
+ struct clk *aclk;
+ u32 cap, cap2;
+
+ /* 1ms tick is generated only for the CCC or DevSleep features */
+ cap = readl(hpriv->mmio + HOST_CAP);
+ cap2 = readl(hpriv->mmio + HOST_CAP2);
+ if (!(cap & HOST_CAP_CCC) && !(cap2 & HOST_CAP2_SDS))
+ return;
+
+ /*
+ * Tick is generated based on the AXI/AHB application clocks signal
+ * so we need to be sure in the clock we are going to use.
+ */
+ aclk = ahci_platform_find_clk(hpriv, "aclk");
+ if (!aclk)
+ return;
+
+ /* 1ms timer interval is set as TIMV = AMBA_FREQ[MHZ] * 1000 */
+ dpriv->timv = readl(hpriv->mmio + AHCI_DWC_HOST_TIMER1MS);
+ dpriv->timv = FIELD_GET(AHCI_DWC_HOST_TIMV_MASK, dpriv->timv);
+ rate = clk_get_rate(aclk) / 1000UL;
+ if (rate == dpriv->timv)
+ return;
+
+ dev_info(&dpriv->pdev->dev, "Update CCC/DevSlp timer for Fapp %lu MHz\n",
+ rate / 1000UL);
+ dpriv->timv = FIELD_PREP(AHCI_DWC_HOST_TIMV_MASK, rate);
+ writel(dpriv->timv, hpriv->mmio + AHCI_DWC_HOST_TIMER1MS);
+}
+
+static int ahci_dwc_init_dmacr(struct ahci_host_priv *hpriv)
+{
+ struct ahci_dwc_host_priv *dpriv = hpriv->plat_data;
+ struct device_node *child;
+ void __iomem *port_mmio;
+ u32 port, dmacr, ts;
+
+ /*
+ * Update the DMA Tx/Rx transaction sizes in accordance with the
+ * platform setup. Note values exceeding maximal or minimal limits will
+ * be automatically clamped. Also note the register isn't affected by
+ * the HBA global reset so we can freely initialize it once until the
+ * next system reset.
+ */
+ for_each_child_of_node(dpriv->pdev->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;
+ }
+
+ port_mmio = __ahci_port_base(hpriv, port);
+ dmacr = readl(port_mmio + AHCI_DWC_PORT_DMACR);
+
+ if (!of_property_read_u32(child, "snps,tx-ts-max", &ts)) {
+ ts = ilog2(ts);
+ dmacr &= ~AHCI_DWC_PORT_TXTS_MASK;
+ dmacr |= FIELD_PREP(AHCI_DWC_PORT_TXTS_MASK, ts);
+ }
+
+ if (!of_property_read_u32(child, "snps,rx-ts-max", &ts)) {
+ ts = ilog2(ts);
+ dmacr &= ~AHCI_DWC_PORT_RXTS_MASK;
+ dmacr |= FIELD_PREP(AHCI_DWC_PORT_RXTS_MASK, ts);
+ }
+
+ writel(dmacr, port_mmio + AHCI_DWC_PORT_DMACR);
+ dpriv->dmacr[port] = dmacr;
+ }
+
+ return 0;
+}
+
+static int ahci_dwc_init_host(struct ahci_host_priv *hpriv)
+{
+ int rc;
+
+ rc = ahci_platform_enable_resources(hpriv);
+ if (rc)
+ return rc;
+
+ ahci_dwc_check_cap(hpriv);
+
+ ahci_dwc_init_timer(hpriv);
+
+ rc = ahci_dwc_init_dmacr(hpriv);
+ if (rc)
+ goto err_disable_resources;
+
+ return 0;
+
+err_disable_resources:
+ ahci_platform_disable_resources(hpriv);
+
+ return rc;
+}
+
+static int ahci_dwc_reinit_host(struct ahci_host_priv *hpriv)
+{
+ struct ahci_dwc_host_priv *dpriv = hpriv->plat_data;
+ unsigned long port_map = hpriv->port_map;
+ void __iomem *port_mmio;
+ int i, rc;
+
+ rc = ahci_platform_enable_resources(hpriv);
+ if (rc)
+ return rc;
+
+ writel(dpriv->timv, hpriv->mmio + AHCI_DWC_HOST_TIMER1MS);
+
+ for_each_set_bit(i, &port_map, AHCI_MAX_PORTS) {
+ port_mmio = __ahci_port_base(hpriv, i);
+ writel(dpriv->dmacr[i], port_mmio + AHCI_DWC_PORT_DMACR);
+ }
+
+ return 0;
+}
+
+static void ahci_dwc_clear_host(struct ahci_host_priv *hpriv)
+{
+ ahci_platform_disable_resources(hpriv);
+}
+
+static void ahci_dwc_stop_host(struct ata_host *host)
+{
+ struct ahci_host_priv *hpriv = host->private_data;
+
+ ahci_dwc_clear_host(hpriv);
+}
+
+static struct ata_port_operations ahci_dwc_port_ops = {
+ .inherits = &ahci_platform_ops,
+ .host_stop = ahci_dwc_stop_host,
+};
+
+static const struct ata_port_info ahci_dwc_port_info = {
+ .flags = AHCI_FLAG_COMMON,
+ .pio_mask = ATA_PIO4,
+ .udma_mask = ATA_UDMA6,
+ .port_ops = &ahci_dwc_port_ops,
+};
+
+static struct scsi_host_template ahci_dwc_scsi_info = {
+ AHCI_SHT(DRV_NAME),
+};
+
+static int ahci_dwc_probe(struct platform_device *pdev)
+{
+ struct ahci_host_priv *hpriv;
+ int rc;
+
+ hpriv = ahci_dwc_get_resources(pdev);
+ if (IS_ERR(hpriv))
+ return PTR_ERR(hpriv);
+
+ rc = ahci_dwc_init_host(hpriv);
+ if (rc)
+ return rc;
+
+ rc = ahci_platform_init_host(pdev, hpriv, &ahci_dwc_port_info,
+ &ahci_dwc_scsi_info);
+ if (rc)
+ goto err_clear_host;
+
+ return 0;
+
+err_clear_host:
+ ahci_dwc_clear_host(hpriv);
+
+ return rc;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int ahci_dwc_suspend(struct device *dev)
+{
+ struct ata_host *host = dev_get_drvdata(dev);
+ struct ahci_host_priv *hpriv = host->private_data;
+ int rc;
+
+ rc = ahci_platform_suspend_host(dev);
+ if (rc)
+ return rc;
+
+ ahci_dwc_clear_host(hpriv);
+
+ return 0;
+}
+
+static int ahci_dwc_resume(struct device *dev)
+{
+ struct ata_host *host = dev_get_drvdata(dev);
+ struct ahci_host_priv *hpriv = host->private_data;
+ int rc;
+
+ rc = ahci_dwc_reinit_host(hpriv);
+ if (rc)
+ return rc;
+
+ return ahci_platform_resume_host(dev);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(ahci_dwc_pm_ops, ahci_dwc_suspend, ahci_dwc_resume);
+
+static const struct of_device_id ahci_dwc_of_match[] = {
+ { .compatible = "snps,dwc-ahci", },
+ { .compatible = "snps,spear-ahci", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, ahci_dwc_of_match);
+
+static struct platform_driver ahci_dwc_driver = {
+ .probe = ahci_dwc_probe,
+ .remove = ata_platform_remove_one,
+ .shutdown = ahci_platform_shutdown,
+ .driver = {
+ .name = DRV_NAME,
+ .of_match_table = ahci_dwc_of_match,
+ .pm = &ahci_dwc_pm_ops,
+ },
+};
+module_platform_driver(ahci_dwc_driver);
+
+MODULE_DESCRIPTION("DWC AHCI SATA platform driver");
+MODULE_AUTHOR("Serge Semin <[email protected]>");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/ata/ahci_platform.c b/drivers/ata/ahci_platform.c
index 9b56490ecbc3..8f5572a9f8f1 100644
--- a/drivers/ata/ahci_platform.c
+++ b/drivers/ata/ahci_platform.c
@@ -80,9 +80,7 @@ static SIMPLE_DEV_PM_OPS(ahci_pm_ops, ahci_platform_suspend,
static const struct of_device_id ahci_of_match[] = {
{ .compatible = "generic-ahci", },
/* Keep the following compatibles for device tree compatibility */
- { .compatible = "snps,spear-ahci", },
{ .compatible = "ibm,476gtr-ahci", },
- { .compatible = "snps,dwc-ahci", },
{ .compatible = "hisilicon,hisi-ahci", },
{ .compatible = "cavium,octeon-7130-ahci", },
{ /* sentinel */ }
--
2.35.1
On 5/12/22 01:18, Serge Semin wrote:
> Synopsys AHCI SATA controller can work pretty under with the generic
> AHCI-platform driver control. But there are vendor-specific peculiarities
> which can tune the device performance up and which may need to be fixed up
> for proper device functioning. In addition some DWC AHCI-based controllers
> may require small platform-specific fixups, so adding them in the generic
> AHCI driver would have ruined the code simplicity. Shortly speaking in
> order to keep the generic AHCI-platform code clean and have DWC AHCI
> SATA-specific features supported we suggest to add a dedicated DWC AHCI
> SATA device driver. Aside with the standard AHCI-platform resources
> getting, enabling/disabling and the controller registration the new driver
> performs the next actions.
>
> First of all there is a way to verify whether the HBA/ports capabilities
> activated in OF are correct. Almost all features availability is reflected
> in the vendor-specific parameters registers. So the DWC AHCI driver does
> the capabilities sanity check based on the corresponding fields state.
>
> Secondly if either the Command Completion Coalescing or the Device Sleep
> feature is enabled the DWC AHCI-specific internal 1ms timer must be fixed
> in accordance with the application clock signal frequency. In particular
> the timer value must be set to be Fapp * 1000. Normally the SoC designers
> pre-configure the TIMER1MS register to contain a correct value by default.
> But the platforms can support the application clock rate change. If that
> happens the 1ms timer value must be accordingly updated otherwise the
> dependent features won't work as expected. In the DWC AHCI driver we
> suggest to rely on the "aclk" reference clock rate to set the timer
> interval up. That clock source is supposed to be the AHCI SATA application
> clock in accordance with the DT bindings.
>
> Finally DWC AHCI SATA controller AXI/AHB bus DMA-engine can be tuned up to
> transfer up to 1024 * FIFO words at a time by setting the Tx/Rx
> transaction size in the DMA control register. The maximum value depends on
> the DMA data bus and AXI/AHB bus maximum burst length. In most of the
> cases it's better to set the maximum possible value to reach the best AHCI
> SATA controller performance. But sometimes in order to improve the system
> interconnect responsiveness, transferring in smaller data chunks may be
> more preferable. For such cases and for the case when the default value
> doesn't provide the best DMA bus performance we suggest to use the new
> HBA-port specific DT-properties "snps,{tx,rx}-ts-max" to tune the DMA
> transactions size up.
>
> After all the settings denoted above are handled the DWC AHCI SATA driver
> proceeds further with the standard AHCI-platform host initializations.
>
> Note since DWC AHCI controller is now have a dedicated driver we can
> discard the corresponding compatible string from the ahci-platform.c
> module. The same concerns "snps,spear-ahci" compatible string, which is
> also based on the DWC AHCI IP-core.
>
> Signed-off-by: Serge Semin <[email protected]>
>
> ---
>
> Note there are three more AHCI SATA drivers which have been created for
> the devices based on the DWC AHCI SATA IP-core. It's AHCI SunXi, St and
> iMX drivers. Mostly they don't support the features implemented in this
> driver. So hopefully sometime in future they can be converted to be based
> on the generic DWC AHCI SATA driver and just perform some
> subvendor-specific setups in their own LLDD (glue) driver code. But for
> now let's leave the generic DWC AHCI SATA code as is. Hopefully the new
> DWC AHCI-based device drivers will try at least to re-use a part of the
> DWC AHCI driver methods if not being able to be integrated in the generic
> DWC driver code.
>
> Changelog v2:
> - Change the local objects prefix from 'dwc_ahci_' to 'ahci_dwc_'.
> (@Damien)
> ---
> drivers/ata/Kconfig | 10 +
> drivers/ata/Makefile | 1 +
> drivers/ata/ahci_dwc.c | 395 ++++++++++++++++++++++++++++++++++++
> drivers/ata/ahci_platform.c | 2 -
> 4 files changed, 406 insertions(+), 2 deletions(-)
> create mode 100644 drivers/ata/ahci_dwc.c
>
Reviewed-by: Hannes Reinecke <[email protected]>
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
[email protected] +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer