Hi, Everyone,
This patch series adds support for the Switchtec MRPC DMA mode.
Switchtec switches supports 2 MRPC interaction modes: MRPC normal mode and
MRPC DMA mode, a new feature in the latest firmware versions. MRPC normal
mode requires the host to read the MRPC command status and output data.
In MRPC DMA mode the command status and output data are pushed directly to
host memory and issues an interrupt upon completion. The advantage of MRPC
DMA mode is avoiding potential high latency response from the Memory Read
TLP.
Additionally, we've made the following changes:
* Improve the efficiency of filling MRPC Input buffer by enabling write
combining on MRPC region of BAR
* Software workaround for delay responded Memory READ TLPs that access
the BAR
* And several bug fixes
Regards,
Wesley
Boris Glimcher (1):
switchtec: Set DMA coherent mask in Switchtec driver
Joey Zhang (1):
switchtec: A temporary variable should be used for the flags of
switchtec_ioctl_event_ctl
Kelvin Cao (2):
switchtec: Remove immediate status check after submit a MRPC command
switchtec: Improve MRPC efficiency by leveraging write combining
Wesley Sheng (1):
switchtec: MRPC DMA mode implementation
drivers/pci/switch/switchtec.c | 154 ++++++++++++++++++++++++++++++++++++-----
include/linux/switchtec.h | 16 +++++
2 files changed, 153 insertions(+), 17 deletions(-)
--
2.7.4
From: Boris Glimcher <[email protected]>
Switchtec hardware supports 64-bit DMA, set the correct DMA mask.
This allows the CMA to allocate larger buffers for memory windows.
Signed-off-by: Boris Glimcher <[email protected]>
Signed-off-by: Wesley Sheng <[email protected]>
---
drivers/pci/switch/switchtec.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index d2bca2d..480107e 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -1237,6 +1237,10 @@ static int switchtec_init_pci(struct switchtec_dev *stdev,
if (rc)
return rc;
+ rc = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
+ if (rc)
+ return rc;
+
pci_set_master(pdev);
stdev->mmio = pcim_iomap_table(pdev)[0];
--
2.7.4
From: Kelvin Cao <[email protected]>
MRPC Input buffer is mostly memory without any side effects, thus we can
improve the access time by enabling write combining on only this region of
the BAR.
In a few places, we still need to flush the WC buffer. To do this, we
simply read from the Outbound Doorbell register seeing reads to this
register are processed by low latency hardware.
Signed-off-by: Kelvin Cao <[email protected]>
Signed-off-by: Wesley Sheng <[email protected]>
---
drivers/pci/switch/switchtec.c | 41 +++++++++++++++++++++++++++++++++++------
1 file changed, 35 insertions(+), 6 deletions(-)
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index a908670..0b8862b 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -113,6 +113,19 @@ static void stuser_set_state(struct switchtec_user *stuser,
static void mrpc_complete_cmd(struct switchtec_dev *stdev);
+static void flush_wc_buf(struct switchtec_dev *stdev)
+{
+ struct ntb_dbmsg_regs __iomem *mmio_dbmsg;
+
+ /*
+ * odb (outbound doorbell) register is processed by low latency
+ * hardware and w/o side effect
+ */
+ mmio_dbmsg = (void __iomem *)stdev->mmio_ntb +
+ SWITCHTEC_NTB_REG_DBMSG_OFFSET;
+ ioread32(&mmio_dbmsg->odb);
+}
+
static void mrpc_cmd_submit(struct switchtec_dev *stdev)
{
/* requires the mrpc_mutex to already be held when called */
@@ -132,6 +145,7 @@ static void mrpc_cmd_submit(struct switchtec_dev *stdev)
stdev->mrpc_busy = 1;
memcpy_toio(&stdev->mmio_mrpc->input_data,
stuser->data, stuser->data_len);
+ flush_wc_buf(stdev);
iowrite32(stuser->cmd, &stdev->mmio_mrpc->cmd);
schedule_delayed_work(&stdev->mrpc_timeout,
@@ -1231,23 +1245,38 @@ static int switchtec_init_pci(struct switchtec_dev *stdev,
struct pci_dev *pdev)
{
int rc;
+ void __iomem *map;
+ unsigned long res_start, res_len;
rc = pcim_enable_device(pdev);
if (rc)
return rc;
- rc = pcim_iomap_regions(pdev, 0x1, KBUILD_MODNAME);
- if (rc)
- return rc;
-
rc = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
if (rc)
return rc;
pci_set_master(pdev);
- stdev->mmio = pcim_iomap_table(pdev)[0];
- stdev->mmio_mrpc = stdev->mmio + SWITCHTEC_GAS_MRPC_OFFSET;
+ res_start = pci_resource_start(pdev, 0);
+ res_len = pci_resource_len(pdev, 0);
+
+ if (!devm_request_mem_region(&pdev->dev, res_start,
+ res_len, KBUILD_MODNAME))
+ return -EBUSY;
+
+ stdev->mmio_mrpc = devm_ioremap_wc(&pdev->dev, res_start,
+ SWITCHTEC_GAS_TOP_CFG_OFFSET);
+ if (!stdev->mmio_mrpc)
+ return -ENOMEM;
+
+ map = devm_ioremap(&pdev->dev,
+ res_start + SWITCHTEC_GAS_TOP_CFG_OFFSET,
+ res_len - SWITCHTEC_GAS_TOP_CFG_OFFSET);
+ if (!map)
+ return -ENOMEM;
+
+ stdev->mmio = map - SWITCHTEC_GAS_TOP_CFG_OFFSET;
stdev->mmio_sw_event = stdev->mmio + SWITCHTEC_GAS_SW_EVENT_OFFSET;
stdev->mmio_sys_info = stdev->mmio + SWITCHTEC_GAS_SYS_INFO_OFFSET;
stdev->mmio_flash_info = stdev->mmio + SWITCHTEC_GAS_FLASH_INFO_OFFSET;
--
2.7.4
From: Kelvin Cao <[email protected]>
After submitting a Firmware Download MRPC command, Switchtec firmware will
delay Management EP BAR MemRd TLP responses by more than 10ms. This is a
firmware limitation. Delayed MemRd completions are problem for systems with
a low Completion Timeout (CTO).
The current driver checks the MRPC status immediately after submitting an
MRPC command, which results in the MemRd TLP that's affected by the above
limitation.
Remove the immediate status check and rely on the check after receiving an
interrupt or timing out.
This is only a software workaround to the READ issue and a proper fix of
this should be done in firmware.
Fixes: 080b47def5e5 ("MicroSemi Switchtec management interface driver")
Signed-off-by: Kelvin Cao <[email protected]>
Signed-off-by: Wesley Sheng <[email protected]>
---
drivers/pci/switch/switchtec.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index 54a8b30..d2bca2d 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -134,10 +134,6 @@ static void mrpc_cmd_submit(struct switchtec_dev *stdev)
stuser->data, stuser->data_len);
iowrite32(stuser->cmd, &stdev->mmio_mrpc->cmd);
- stuser->status = ioread32(&stdev->mmio_mrpc->status);
- if (stuser->status != SWITCHTEC_MRPC_STATUS_INPROGRESS)
- mrpc_complete_cmd(stdev);
-
schedule_delayed_work(&stdev->mrpc_timeout,
msecs_to_jiffies(500));
}
--
2.7.4
From: Joey Zhang <[email protected]>
For nr_idxs is larger than 1 switchtec_ioctl_event_ctl event flags will be
used by each event indexes. In current implementation the event flags are
overwritten by first call of the function event_ctl().
Preserve the event flag value with a temporary variable.
Fixes: 52eabba5bcdb ("switchtec: Add IOCTLs to the Switchtec driver")
Signed-off-by: Joey Zhang <[email protected]>
Signed-off-by: Wesley Sheng <[email protected]>
---
drivers/pci/switch/switchtec.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index 480107e..a908670 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -796,6 +796,7 @@ static int ioctl_event_ctl(struct switchtec_dev *stdev,
{
int ret;
int nr_idxs;
+ unsigned int event_flags;
struct switchtec_ioctl_event_ctl ctl;
if (copy_from_user(&ctl, uctl, sizeof(ctl)))
@@ -817,7 +818,9 @@ static int ioctl_event_ctl(struct switchtec_dev *stdev,
else
return -EINVAL;
+ event_flags = ctl.flags;
for (ctl.index = 0; ctl.index < nr_idxs; ctl.index++) {
+ ctl.flags = event_flags;
ret = event_ctl(stdev, &ctl);
if (ret < 0)
return ret;
--
2.7.4
MRPC normal mode requires the host to read the MRPC command status and
output data from BAR. This results in high latency responses from the
Memory Read TLP and potential Completion Timeout (CTO).
MRPC DMA mode implementation includes:
Macro definitions for registers and data structures corresponding to
MRPC DMA mode.
Add module parameter use_dma_mrpc to select between MRPC DMA mode and
MRPC normal mode.
Add MRPC mode functionality to:
* Retrieve MRPC DMA mode version
* Allocate DMA buffer, ISR registration, and enable DMA function during
initialization
* Check MRPC execution status and collect execution results from DMA buffer
* Release DMA buffer and disable DMA function when unloading module
MRPC DMA mode is a new feature of firmware and the driver will fall back
to MRPC normal mode if there is no support in the legacy firmware.
Include <linux/io-64-nonatomic-lo-hi.h> so that readq/writeq is replaced
by two readl/writel on systems that do not support it.
Signed-off-by: Wesley Sheng <[email protected]>
---
drivers/pci/switch/switchtec.c | 108 +++++++++++++++++++++++++++++++++++++----
include/linux/switchtec.h | 16 ++++++
2 files changed, 114 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index 0b8862b..6b726cb 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -13,7 +13,7 @@
#include <linux/uaccess.h>
#include <linux/poll.h>
#include <linux/wait.h>
-
+#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/nospec.h>
MODULE_DESCRIPTION("Microsemi Switchtec(tm) PCIe Management Driver");
@@ -25,6 +25,11 @@ static int max_devices = 16;
module_param(max_devices, int, 0644);
MODULE_PARM_DESC(max_devices, "max number of switchtec device instances");
+static bool use_dma_mrpc = 1;
+module_param(use_dma_mrpc, bool, 0644);
+MODULE_PARM_DESC(use_dma_mrpc,
+ "Enable the use of the DMA MRPC feature");
+
static dev_t switchtec_devt;
static DEFINE_IDA(switchtec_minor_ida);
@@ -141,6 +146,11 @@ static void mrpc_cmd_submit(struct switchtec_dev *stdev)
stuser = list_entry(stdev->mrpc_queue.next, struct switchtec_user,
list);
+ if (stdev->dma_mrpc) {
+ stdev->dma_mrpc->status = SWITCHTEC_MRPC_STATUS_INPROGRESS;
+ memset(stdev->dma_mrpc->data, 0xFF, SWITCHTEC_MRPC_PAYLOAD_SIZE);
+ }
+
stuser_set_state(stuser, MRPC_RUNNING);
stdev->mrpc_busy = 1;
memcpy_toio(&stdev->mmio_mrpc->input_data,
@@ -180,7 +190,11 @@ static void mrpc_complete_cmd(struct switchtec_dev *stdev)
stuser = list_entry(stdev->mrpc_queue.next, struct switchtec_user,
list);
- stuser->status = ioread32(&stdev->mmio_mrpc->status);
+ if (stdev->dma_mrpc)
+ stuser->status = stdev->dma_mrpc->status;
+ else
+ stuser->status = ioread32(&stdev->mmio_mrpc->status);
+
if (stuser->status == SWITCHTEC_MRPC_STATUS_INPROGRESS)
return;
@@ -190,13 +204,19 @@ static void mrpc_complete_cmd(struct switchtec_dev *stdev)
if (stuser->status != SWITCHTEC_MRPC_STATUS_DONE)
goto out;
- stuser->return_code = ioread32(&stdev->mmio_mrpc->ret_value);
+ if (stdev->dma_mrpc)
+ stuser->return_code = stdev->dma_mrpc->rtn_code;
+ else
+ stuser->return_code = ioread32(&stdev->mmio_mrpc->ret_value);
if (stuser->return_code != 0)
goto out;
- memcpy_fromio(stuser->data, &stdev->mmio_mrpc->output_data,
- stuser->read_len);
-
+ if (stdev->dma_mrpc)
+ memcpy(stuser->data, &stdev->dma_mrpc->data,
+ stuser->read_len);
+ else
+ memcpy_fromio(stuser->data, &stdev->mmio_mrpc->output_data,
+ stuser->read_len);
out:
complete_all(&stuser->comp);
list_del_init(&stuser->list);
@@ -231,7 +251,10 @@ static void mrpc_timeout_work(struct work_struct *work)
mutex_lock(&stdev->mrpc_mutex);
- status = ioread32(&stdev->mmio_mrpc->status);
+ if (stdev->dma_mrpc)
+ status = stdev->dma_mrpc->status;
+ else
+ status = ioread32(&stdev->mmio_mrpc->status);
if (status == SWITCHTEC_MRPC_STATUS_INPROGRESS) {
schedule_delayed_work(&stdev->mrpc_timeout,
msecs_to_jiffies(500));
@@ -239,7 +262,6 @@ static void mrpc_timeout_work(struct work_struct *work)
}
mrpc_complete_cmd(stdev);
-
out:
mutex_unlock(&stdev->mrpc_mutex);
}
@@ -1030,10 +1052,24 @@ static void enable_link_state_events(struct switchtec_dev *stdev)
}
}
+static void enable_dma_mrpc(struct switchtec_dev *stdev)
+{
+ writeq(stdev->dma_mrpc_dma_addr, &stdev->mmio_mrpc->dma_addr);
+ flush_wc_buf(stdev);
+ iowrite32(SWITCHTEC_DMA_MRPC_EN, &stdev->mmio_mrpc->dma_en);
+}
+
static void stdev_release(struct device *dev)
{
struct switchtec_dev *stdev = to_stdev(dev);
+ if (stdev->dma_mrpc) {
+ iowrite32(0, &stdev->mmio_mrpc->dma_en);
+ flush_wc_buf(stdev);
+ writeq(0, &stdev->mmio_mrpc->dma_addr);
+ dma_free_coherent(&stdev->pdev->dev, sizeof(*stdev->dma_mrpc),
+ stdev->dma_mrpc, stdev->dma_mrpc_dma_addr);
+ }
kfree(stdev);
}
@@ -1189,10 +1225,27 @@ static irqreturn_t switchtec_event_isr(int irq, void *dev)
return ret;
}
+
+static irqreturn_t switchtec_dma_mrpc_isr(int irq, void *dev)
+{
+ struct switchtec_dev *stdev = dev;
+ irqreturn_t ret = IRQ_NONE;
+
+ iowrite32(SWITCHTEC_EVENT_CLEAR |
+ SWITCHTEC_EVENT_EN_IRQ,
+ &stdev->mmio_part_cfg->mrpc_comp_hdr);
+ schedule_work(&stdev->mrpc_work);
+
+ ret = IRQ_HANDLED;
+ return ret;
+}
+
static int switchtec_init_isr(struct switchtec_dev *stdev)
{
int nvecs;
int event_irq;
+ int dma_mrpc_irq;
+ int rc;
nvecs = pci_alloc_irq_vectors(stdev->pdev, 1, 4,
PCI_IRQ_MSIX | PCI_IRQ_MSI);
@@ -1207,9 +1260,29 @@ static int switchtec_init_isr(struct switchtec_dev *stdev)
if (event_irq < 0)
return event_irq;
- return devm_request_irq(&stdev->pdev->dev, event_irq,
+ rc = devm_request_irq(&stdev->pdev->dev, event_irq,
switchtec_event_isr, 0,
KBUILD_MODNAME, stdev);
+
+ if (rc)
+ return rc;
+
+ if (!stdev->dma_mrpc)
+ return rc;
+
+ dma_mrpc_irq = ioread32(&stdev->mmio_mrpc->dma_vector);
+ if (dma_mrpc_irq < 0 || dma_mrpc_irq >= nvecs)
+ return -EFAULT;
+
+ dma_mrpc_irq = pci_irq_vector(stdev->pdev, dma_mrpc_irq);
+ if (dma_mrpc_irq < 0)
+ return dma_mrpc_irq;
+
+ rc = devm_request_irq(&stdev->pdev->dev, dma_mrpc_irq,
+ switchtec_dma_mrpc_isr, 0,
+ KBUILD_MODNAME, stdev);
+
+ return rc;
}
static void init_pff(struct switchtec_dev *stdev)
@@ -1294,6 +1367,19 @@ static int switchtec_init_pci(struct switchtec_dev *stdev,
pci_set_drvdata(pdev, stdev);
+ if (!use_dma_mrpc)
+ return 0;
+
+ if (!(ioread32(&stdev->mmio_mrpc->dma_ver) ? true : false))
+ return 0;
+
+ stdev->dma_mrpc = dma_zalloc_coherent(&stdev->pdev->dev,
+ sizeof(*stdev->dma_mrpc),
+ &stdev->dma_mrpc_dma_addr,
+ GFP_KERNEL);
+ if (stdev->dma_mrpc == NULL)
+ return -ENOMEM;
+
return 0;
}
@@ -1325,6 +1411,9 @@ static int switchtec_pci_probe(struct pci_dev *pdev,
&stdev->mmio_part_cfg->mrpc_comp_hdr);
enable_link_state_events(stdev);
+ if (stdev->dma_mrpc)
+ enable_dma_mrpc(stdev);
+
rc = cdev_device_add(&stdev->cdev, &stdev->dev);
if (rc)
goto err_devadd;
@@ -1350,7 +1439,6 @@ static void switchtec_pci_remove(struct pci_dev *pdev)
cdev_device_del(&stdev->cdev, &stdev->dev);
ida_simple_remove(&switchtec_minor_ida, MINOR(stdev->dev.devt));
dev_info(&stdev->dev, "unregistered.\n");
-
stdev_kill(stdev);
put_device(&stdev->dev);
}
diff --git a/include/linux/switchtec.h b/include/linux/switchtec.h
index ab400af..eee0412 100644
--- a/include/linux/switchtec.h
+++ b/include/linux/switchtec.h
@@ -29,6 +29,7 @@
#define SWITCHTEC_EVENT_EN_IRQ BIT(3)
#define SWITCHTEC_EVENT_FATAL BIT(4)
+#define SWITCHTEC_DMA_MRPC_EN BIT(0)
enum {
SWITCHTEC_GAS_MRPC_OFFSET = 0x0000,
SWITCHTEC_GAS_TOP_CFG_OFFSET = 0x1000,
@@ -46,6 +47,10 @@ struct mrpc_regs {
u32 cmd;
u32 status;
u32 ret_value;
+ u32 dma_en;
+ u64 dma_addr;
+ u32 dma_vector;
+ u32 dma_ver;
} __packed;
enum mrpc_status {
@@ -342,6 +347,14 @@ struct pff_csr_regs {
struct switchtec_ntb;
+struct dma_mrpc_output {
+ u32 status;
+ u32 cmd_id;
+ u32 rtn_code;
+ u32 output_size;
+ u8 data[SWITCHTEC_MRPC_PAYLOAD_SIZE];
+};
+
struct switchtec_dev {
struct pci_dev *pdev;
struct device dev;
@@ -381,6 +394,9 @@ struct switchtec_dev {
u8 link_event_count[SWITCHTEC_MAX_PFF_CSR];
struct switchtec_ntb *sndev;
+
+ struct dma_mrpc_output *dma_mrpc;
+ dma_addr_t dma_mrpc_dma_addr;
};
static inline struct switchtec_dev *to_stdev(struct device *dev)
--
2.7.4
On 15/11/18 02:43 AM, Wesley Sheng wrote:
> Hi, Everyone,
>
> This patch series adds support for the Switchtec MRPC DMA mode.
I've reviewed this series from it's conception on github[1] and would
like to see it land in the upstream driver, so for the entire series:
Reviewed-by: Logan Gunthorpe <[email protected]>
Thanks,
Logan
[1] https://github.com/Microsemi/switchtec-kernel