[PATCH v2] i3c: master: cdns: add data hold delay support

[Przemyslaw Gaj <pgaj@cadence.com>]

This patch adds support for THD_DEL (Data Hold Delay) to Cadence
I3C master constoller driver.

As per MIPI I3C Specification 1.0, Table 75 (page 142) defines
non-zero minimal tHD_PP timing on master output (Fig 65). This
setting allows to meet this timing on master's soc outputs,
regardless of PCB balancing.

Signed-off-by: Przemyslaw Gaj <pgaj@cadence.com>

---

Main changes between v1 and v2:
- Add device-specific data which holds the thd_del value
- Remove device tree property
---
 drivers/i3c/master/i3c-master-cdns.c | 37 +++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/drivers/i3c/master/i3c-master-cdns.c b/drivers/i3c/master/i3c-master-cdns.c
index 10db0bf0655a..3531396f04fd 100644
--- a/drivers/i3c/master/i3c-master-cdns.c
+++ b/drivers/i3c/master/i3c-master-cdns.c
@@ -22,6 +22,7 @@
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>
+#include <linux/of_device.h>
 
 #define DEV_ID				0x0
 #define DEV_ID_I3C_MASTER		0x5034
@@ -60,6 +61,7 @@
 #define CTRL_HALT_EN			BIT(30)
 #define CTRL_MCS			BIT(29)
 #define CTRL_MCS_EN			BIT(28)
+#define CTRL_THD_DEL(x)			(((x) << 24) & GENMASK(25, 24))
 #define CTRL_HJ_DISEC			BIT(8)
 #define CTRL_MST_ACK			BIT(7)
 #define CTRL_HJ_ACK			BIT(6)
@@ -388,6 +390,10 @@ struct cdns_i3c_xfer {
 	struct cdns_i3c_cmd cmds[0];
 };
 
+struct cdns_i3c_data {
+	u8 thd_del;
+};
+
 struct cdns_i3c_master {
 	struct work_struct hj_work;
 	struct i3c_master_controller base;
@@ -408,6 +414,7 @@ struct cdns_i3c_master {
 	struct clk *pclk;
 	struct cdns_i3c_master_caps caps;
 	unsigned long i3c_scl_lim;
+	const struct cdns_i3c_data *devdata;
 };
 
 static inline struct cdns_i3c_master *
@@ -1264,6 +1271,15 @@ static int cdns_i3c_master_bus_init(struct i3c_master_controller *m)
 	 * We will issue ENTDAA afterwards from the threaded IRQ handler.
 	 */
 	ctrl |= CTRL_HJ_ACK | CTRL_HJ_DISEC | CTRL_HALT_EN | CTRL_MCS_EN;
+
+	/*
+	 * Configure data hold delay based on device-specific data.
+	 *
+	 * MIPI I3C Specification 1.0 defines non-zero minimal tHD_PP timing on
+	 * master output. This setting allows to meet this timing on master's
+	 * SoC outputs, regardless of PCB balancing.
+	 */
+	ctrl |= CTRL_THD_DEL(master->devdata->thd_del);
 	writel(ctrl, master->regs + CTRL);
 
 	cdns_i3c_master_enable(master);
@@ -1521,17 +1537,33 @@ static void cdns_i3c_master_hj(struct work_struct *work)
 	i3c_master_do_daa(&master->base);
 }
 
+static struct cdns_i3c_data cdns_i3c_devdata = {
+	.thd_del = 0x3,
+};
+
+static const struct of_device_id cdns_i3c_master_of_ids[] = {
+	{ .compatible = "cdns,i3c-master", .data = &cdns_i3c_devdata },
+	{ /* sentinel */ },
+};
+
 static int cdns_i3c_master_probe(struct platform_device *pdev)
 {
 	struct cdns_i3c_master *master;
+	const struct of_device_id *of_id = of_match_device(
+		of_match_ptr(cdns_i3c_master_of_ids), &pdev->dev);
 	struct resource *res;
 	int ret, irq;
 	u32 val;
 
+	if (!of_id)
+		return -ENODEV;
+
 	master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL);
 	if (!master)
 		return -ENOMEM;
 
+	master->devdata = of_id->data;
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	master->regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(master->regs))
@@ -1631,11 +1663,6 @@ static int cdns_i3c_master_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static const struct of_device_id cdns_i3c_master_of_ids[] = {
-	{ .compatible = "cdns,i3c-master" },
-	{ /* sentinel */ },
-};
-
 static struct platform_driver cdns_i3c_master = {
 	.probe = cdns_i3c_master_probe,
 	.remove = cdns_i3c_master_remove,
-- 
2.14.0


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