[RFC PATCH net-next 2/6] net: ethernet: add mac-phy interrupt support with reset complete handling

From: Parthiban Veerasooran
Date: Fri Sep 08 2023 - 10:30:16 EST

Register MAC-PHY interrupt and handle reset complete interrupt. Reset
complete bit is set when the MAC-PHY reset complete and ready for
configuration. When it is set, it will generate a non-maskable interrupt
to alert the SPI host. Additionally reset complete bit in the STS0
register has to be written by one upon reset complete to clear the
interrupt.

Signed-off-by: Parthiban Veerasooran <Parthiban.Veerasooran@xxxxxxxxxxxxx>
---
drivers/net/ethernet/oa_tc6.c | 141 ++++++++++++++++++++++++++++++++--
include/linux/oa_tc6.h | 16 +++-
2 files changed, 150 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/oa_tc6.c b/drivers/net/ethernet/oa_tc6.c
index 613cf034430a..0019f70345b6 100644
--- a/drivers/net/ethernet/oa_tc6.c
+++ b/drivers/net/ethernet/oa_tc6.c
@@ -6,6 +6,7 @@
*/

#include <linux/bitfield.h>
+#include <linux/interrupt.h>
#include <linux/oa_tc6.h>

static int oa_tc6_spi_transfer(struct spi_device *spi, u8 *ptx, u8 *prx,
@@ -160,10 +161,16 @@ int oa_tc6_perform_ctrl(struct oa_tc6 *tc6, u32 addr, u32 val[], u8 len,
if (ret)
goto err_ctrl;

- /* Check echoed/received control reply */
- ret = oa_tc6_check_control(tc6, tx_buf, rx_buf, len, wnr, ctrl_prot);
- if (ret)
- goto err_ctrl;
+ /* In case of reset write, the echoed control command doesn't have any
+ * valid data. So no need to check for error.
+ */
+ if (addr != OA_TC6_RESET) {
+ /* Check echoed/received control reply */
+ ret = oa_tc6_check_control(tc6, tx_buf, rx_buf, len, wnr,
+ ctrl_prot);
+ if (ret)
+ goto err_ctrl;
+ }

if (!wnr) {
/* Copy read data from the rx data in case of ctrl read */
@@ -186,6 +193,88 @@ int oa_tc6_perform_ctrl(struct oa_tc6 *tc6, u32 addr, u32 val[], u8 len,
return ret;
}

+static int oa_tc6_handler(void *data)
+{
+ struct oa_tc6 *tc6 = data;
+ u32 regval;
+ int ret;
+
+ while (likely(!kthread_should_stop())) {
+ wait_event_interruptible(tc6->tc6_wq, tc6->int_flag ||
+ kthread_should_stop());
+ if (tc6->int_flag) {
+ tc6->int_flag = false;
+ ret = oa_tc6_perform_ctrl(tc6, OA_TC6_STS0, &regval, 1,
+ false, false);
+ if (ret) {
+ dev_err(&tc6->spi->dev, "Failed to read STS0\n");
+ continue;
+ }
+ /* Check for reset complete interrupt status */
+ if (regval & RESETC) {
+ regval = RESETC;
+ /* SPI host should write RESETC bit with one to
+ * clear the reset interrupt status.
+ */
+ ret = oa_tc6_perform_ctrl(tc6, OA_TC6_STS0,
+ &regval, 1, true,
+ false);
+ if (ret) {
+ dev_err(&tc6->spi->dev,
+ "Failed to write STS0\n");
+ continue;
+ }
+ complete(&tc6->rst_complete);
+ }
+ }
+ }
+ return 0;
+}
+
+static irqreturn_t macphy_irq(int irq, void *dev_id)
+{
+ struct oa_tc6 *tc6 = dev_id;
+
+ /* Wake tc6 task to perform interrupt action */
+ tc6->int_flag = true;
+ wake_up_interruptible(&tc6->tc6_wq);
+
+ return IRQ_HANDLED;
+}
+
+static int oa_tc6_sw_reset(struct oa_tc6 *tc6)
+{
+ long timeleft;
+ u32 regval;
+ int ret;
+
+ /* Perform software reset with both protected and unprotected control
+ * commands because the driver doesn't know the current status of the
+ * MAC-PHY.
+ */
+ regval = SW_RESET;
+ reinit_completion(&tc6->rst_complete);
+ ret = oa_tc6_perform_ctrl(tc6, OA_TC6_RESET, &regval, 1, true, false);
+ if (ret) {
+ dev_err(&tc6->spi->dev, "RESET register write failed\n");
+ return ret;
+ }
+
+ ret = oa_tc6_perform_ctrl(tc6, OA_TC6_RESET, &regval, 1, true, true);
+ if (ret) {
+ dev_err(&tc6->spi->dev, "RESET register write failed\n");
+ return ret;
+ }
+ timeleft = wait_for_completion_interruptible_timeout(&tc6->rst_complete,
+ msecs_to_jiffies(1));
+ if (timeleft <= 0) {
+ dev_err(&tc6->spi->dev, "MAC-PHY reset failed\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
int oa_tc6_write_register(struct oa_tc6 *tc6, u32 addr, u32 val[], u8 len)
{
return oa_tc6_perform_ctrl(tc6, addr, val, len, true, tc6->ctrl_prot);
@@ -201,6 +290,7 @@ EXPORT_SYMBOL_GPL(oa_tc6_read_register);
struct oa_tc6 *oa_tc6_init(struct spi_device *spi)
{
struct oa_tc6 *tc6;
+ int ret;

if (!spi)
return NULL;
@@ -211,12 +301,51 @@ struct oa_tc6 *oa_tc6_init(struct spi_device *spi)

tc6->spi = spi;

+ /* Used for triggering the OA TC6 task */
+ init_waitqueue_head(&tc6->tc6_wq);
+
+ init_completion(&tc6->rst_complete);
+
+ /* This task performs the SPI transfer */
+ tc6->tc6_task = kthread_run(oa_tc6_handler, tc6, "OA TC6 Task");
+ if (IS_ERR(tc6->tc6_task))
+ goto err_tc6_task;
+
+ /* Set the highest priority to the tc6 task as it is time critical */
+ sched_set_fifo(tc6->tc6_task);
+
+ /* Register MAC-PHY interrupt service routine */
+ ret = devm_request_irq(&spi->dev, spi->irq, macphy_irq, 0, "macphy int",
+ tc6);
+ if ((ret != -ENOTCONN) && ret < 0) {
+ dev_err(&spi->dev, "Error attaching macphy irq %d\n", ret);
+ goto err_macphy_irq;
+ }
+
+ /* Perform MAC-PHY software reset */
+ if (oa_tc6_sw_reset(tc6))
+ goto err_macphy_reset;
+
return tc6;
+
+err_macphy_reset:
+ devm_free_irq(&tc6->spi->dev, tc6->spi->irq, tc6);
+err_macphy_irq:
+ kthread_stop(tc6->tc6_task);
+err_tc6_task:
+ kfree(tc6);
+ return NULL;
}
EXPORT_SYMBOL_GPL(oa_tc6_init);

-void oa_tc6_deinit(struct oa_tc6 *tc6)
+int oa_tc6_deinit(struct oa_tc6 *tc6)
{
- kfree(tc6);
+ int ret;
+
+ devm_free_irq(&tc6->spi->dev, tc6->spi->irq, tc6);
+ ret = kthread_stop(tc6->tc6_task);
+ if (!ret)
+ kfree(tc6);
+ return ret;
}
EXPORT_SYMBOL_GPL(oa_tc6_deinit);
diff --git a/include/linux/oa_tc6.h b/include/linux/oa_tc6.h
index 5e0a58ab1dcd..315f061c2dfe 100644
--- a/include/linux/oa_tc6.h
+++ b/include/linux/oa_tc6.h
@@ -17,15 +17,29 @@
#define CTRL_HDR_LEN GENMASK(7, 1) /* Length */
#define CTRL_HDR_P BIT(0) /* Parity Bit */

+/* Open Alliance TC6 Standard Control and Status Registers */
+#define OA_TC6_RESET 0x0003 /* Reset Control and Status Register */
+#define OA_TC6_STS0 0x0008 /* Status Register #0 */
+
+/* RESET register field */
+#define SW_RESET BIT(0) /* Software Reset */
+
+/* STATUS0 register field */
+#define RESETC BIT(6) /* Reset Complete */
+
#define TC6_HDR_SIZE 4 /* Ctrl command header size as per OA */
#define TC6_FTR_SIZE 4 /* Ctrl command footer size ss per OA */

struct oa_tc6 {
struct spi_device *spi;
bool ctrl_prot;
+ struct task_struct *tc6_task;
+ wait_queue_head_t tc6_wq;
+ bool int_flag;
+ struct completion rst_complete;
};

struct oa_tc6 *oa_tc6_init(struct spi_device *spi);
-void oa_tc6_deinit(struct oa_tc6 *tc6);
+int oa_tc6_deinit(struct oa_tc6 *tc6);
int oa_tc6_write_register(struct oa_tc6 *tc6, u32 addr, u32 value[], u8 len);
int oa_tc6_read_register(struct oa_tc6 *tc6, u32 addr, u32 value[], u8 len);
--
2.34.1