Merge tag 'i3c/for-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux

Pull i3c updates from Alexandre Belloni:
 "We are continuing to see more fixes as hardware is available and code
  is actually getting tested.

  Core:
   - Add a sysfs control for hotjoin
   - Add fallback method for GETMXDS CCC

  Drivers:
   - cdns: fix prescale for i2c clock
   - mipi-i3c-hci: more fixes now that the driver is used
   - svc: hotjoin enabling/disabling support"

* tag 'i3c/for-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux:
  i3c: document hotjoin sysfs entry
  i3c: master: fix kernel-doc check warning
  i3c: master: cdns: Update maximum prescaler value for i2c clock
  i3c: master: fix Excess kernel-doc description warning
  i3c: master: svc: return actual transfer data len
  i3c: master: svc: rename read_len as actual_len
  i3c: add actual_len in i3c_priv_xfer
  i3c: master: svc: add hot join support
  i3c: master: add enable(disable) hot join in sys entry
  i3c: master: Fix build error
  i3c: Add fallback method for GETMXDS CCC
  i3c: mipi-i3c-hci: Add DMA bounce buffer for private transfers
  i3c: mipi-i3c-hci: Handle I3C address header error in hci_cmd_v1_daa()
  i3c: mipi-i3c-hci: Do not overallocate transfers in hci_cmd_v1_daa()
  i3c: mipi-i3c-hci: Report NACK response from CCC command to core

Author: torvalds

Documentation/ABI/testing/sysfs-bus-i3c

@@ -88,6 +88,21 @@ Description:
 		This entry describes the HDRCAP of the master controller
 		driving the bus.
 
+What:		/sys/bus/i3c/devices/i3c-<bus-id>/hotjoin
+KernelVersion:  6.8
+Contact:	linux-i3c@vger.kernel.org
+Description:
+		I3C’s Hot-Join mechanism allows an I3C Device to inform the
+		Active Controller that a newly-joined Target is present on the
+		I3C Bus and is ready to receive a Dynamic Address, in order to
+		become fully functional on the Bus. Hot-Join is used when the
+		Target is mounted on the same I3C bus and remains depowered
+		until needed or until the Target is physically inserted into the
+		I3C bus
+
+		This entry allows to enable or disable Hot-join of the Current
+		Controller driving the bus.
+
 What:		/sys/bus/i3c/devices/i3c-<bus-id>/<bus-id>-<device-pid>
 KernelVersion:  5.0
 Contact:	linux-i3c@vger.kernel.org

drivers/i3c/master.c

@@ -557,6 +557,88 @@ static ssize_t i2c_scl_frequency_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(i2c_scl_frequency);
 
+static int i3c_set_hotjoin(struct i3c_master_controller *master, bool enable)
+{
+	int ret;
+
+	if (!master || !master->ops)
+		return -EINVAL;
+
+	if (!master->ops->enable_hotjoin || !master->ops->disable_hotjoin)
+		return -EINVAL;
+
+	i3c_bus_normaluse_lock(&master->bus);
+
+	if (enable)
+		ret = master->ops->enable_hotjoin(master);
+	else
+		ret = master->ops->disable_hotjoin(master);
+
+	master->hotjoin = enable;
+
+	i3c_bus_normaluse_unlock(&master->bus);
+
+	return ret;
+}
+
+static ssize_t hotjoin_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct i3c_bus *i3cbus = dev_to_i3cbus(dev);
+	int ret;
+	bool res;
+
+	if (!i3cbus->cur_master)
+		return -EINVAL;
+
+	if (kstrtobool(buf, &res))
+		return -EINVAL;
+
+	ret = i3c_set_hotjoin(i3cbus->cur_master->common.master, res);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+/*
+ * i3c_master_enable_hotjoin - Enable hotjoin
+ * @master: I3C master object
+ *
+ * Return: a 0 in case of success, an negative error code otherwise.
+ */
+int i3c_master_enable_hotjoin(struct i3c_master_controller *master)
+{
+	return i3c_set_hotjoin(master, true);
+}
+EXPORT_SYMBOL_GPL(i3c_master_enable_hotjoin);
+
+/*
+ * i3c_master_disable_hotjoin - Disable hotjoin
+ * @master: I3C master object
+ *
+ * Return: a 0 in case of success, an negative error code otherwise.
+ */
+int i3c_master_disable_hotjoin(struct i3c_master_controller *master)
+{
+	return i3c_set_hotjoin(master, false);
+}
+EXPORT_SYMBOL_GPL(i3c_master_disable_hotjoin);
+
+static ssize_t hotjoin_show(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct i3c_bus *i3cbus = dev_to_i3cbus(dev);
+	ssize_t ret;
+
+	i3c_bus_normaluse_lock(i3cbus);
+	ret = sysfs_emit(buf, "%d\n", i3cbus->cur_master->common.master->hotjoin);
+	i3c_bus_normaluse_unlock(i3cbus);
+
+	return ret;
+}
+
+static DEVICE_ATTR_RW(hotjoin);
+
 static struct attribute *i3c_masterdev_attrs[] = {
 	&dev_attr_mode.attr,
 	&dev_attr_current_master.attr,
@@ -567,6 +649,7 @@ static struct attribute *i3c_masterdev_attrs[] = {
 	&dev_attr_pid.attr,
 	&dev_attr_dynamic_address.attr,
 	&dev_attr_hdrcap.attr,
+	&dev_attr_hotjoin.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(i3c_masterdev);
@@ -1130,8 +1213,16 @@ static int i3c_master_getmxds_locked(struct i3c_master_controller *master,
 
 	i3c_ccc_cmd_init(&cmd, true, I3C_CCC_GETMXDS, &dest, 1);
 	ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
-	if (ret)
-		goto out;
+	if (ret) {
+		/*
+		 * Retry when the device does not support max read turnaround
+		 * while expecting shorter length from this CCC command.
+		 */
+		dest.payload.len -= 3;
+		ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
+		if (ret)
+			goto out;
+	}
 
 	if (dest.payload.len != 2 && dest.payload.len != 5) {
 		ret = -EIO;

drivers/i3c/master/i3c-master-cdns.c

@@ -76,7 +76,8 @@
 #define PRESCL_CTRL0			0x14
 #define PRESCL_CTRL0_I2C(x)		((x) << 16)
 #define PRESCL_CTRL0_I3C(x)		(x)
-#define PRESCL_CTRL0_MAX		GENMASK(9, 0)
+#define PRESCL_CTRL0_I3C_MAX		GENMASK(9, 0)
+#define PRESCL_CTRL0_I2C_MAX		GENMASK(15, 0)
 
 #define PRESCL_CTRL1			0x18
 #define PRESCL_CTRL1_PP_LOW_MASK	GENMASK(15, 8)
@@ -1233,7 +1234,7 @@ static int cdns_i3c_master_bus_init(struct i3c_master_controller *m)
 		return -EINVAL;
 
 	pres = DIV_ROUND_UP(sysclk_rate, (bus->scl_rate.i3c * 4)) - 1;
-	if (pres > PRESCL_CTRL0_MAX)
+	if (pres > PRESCL_CTRL0_I3C_MAX)
 		return -ERANGE;
 
 	bus->scl_rate.i3c = sysclk_rate / ((pres + 1) * 4);
@@ -1246,7 +1247,7 @@ static int cdns_i3c_master_bus_init(struct i3c_master_controller *m)
 	max_i2cfreq = bus->scl_rate.i2c;
 
 	pres = (sysclk_rate / (max_i2cfreq * 5)) - 1;
-	if (pres > PRESCL_CTRL0_MAX)
+	if (pres > PRESCL_CTRL0_I2C_MAX)
 		return -ERANGE;
 
 	bus->scl_rate.i2c = sysclk_rate / ((pres + 1) * 5);

drivers/i3c/master/mipi-i3c-hci/cmd_v1.c

@@ -298,7 +298,7 @@ static int hci_cmd_v1_daa(struct i3c_hci *hci)
 	unsigned int dcr, bcr;
 	DECLARE_COMPLETION_ONSTACK(done);
 
-	xfer = hci_alloc_xfer(2);
+	xfer = hci_alloc_xfer(1);
 	if (!xfer)
 		return -ENOMEM;
 
@@ -339,12 +339,13 @@ static int hci_cmd_v1_daa(struct i3c_hci *hci)
 			ret = -ETIME;
 			break;
 		}
-		if (RESP_STATUS(xfer[0].response) == RESP_ERR_NACK &&
+		if ((RESP_STATUS(xfer->response) == RESP_ERR_ADDR_HEADER ||
+		     RESP_STATUS(xfer->response) == RESP_ERR_NACK) &&
 		    RESP_DATA_LENGTH(xfer->response) == 1) {
 			ret = 0;  /* no more devices to be assigned */
 			break;
 		}
-		if (RESP_STATUS(xfer[0].response) != RESP_SUCCESS) {
+		if (RESP_STATUS(xfer->response) != RESP_SUCCESS) {
 			ret = -EIO;
 			break;
 		}

drivers/i3c/master/mipi-i3c-hci/core.c

@@ -245,7 +245,14 @@ static int i3c_hci_send_ccc_cmd(struct i3c_master_controller *m,
 		if (ccc->rnw)
 			ccc->dests[i - prefixed].payload.len =
 				RESP_DATA_LENGTH(xfer[i].response);
-		if (RESP_STATUS(xfer[i].response) != RESP_SUCCESS) {
+		switch (RESP_STATUS(xfer[i].response)) {
+		case RESP_SUCCESS:
+			continue;
+		case RESP_ERR_ADDR_HEADER:
+		case RESP_ERR_NACK:
+			ccc->err = I3C_ERROR_M2;
+			fallthrough;
+		default:
 			ret = -EIO;
 			goto out;
 		}
@@ -269,6 +276,34 @@ static int i3c_hci_daa(struct i3c_master_controller *m)
 	return hci->cmd->perform_daa(hci);
 }
 
+static int i3c_hci_alloc_safe_xfer_buf(struct i3c_hci *hci,
+				       struct hci_xfer *xfer)
+{
+	if (hci->io != &mipi_i3c_hci_dma ||
+	    xfer->data == NULL || !is_vmalloc_addr(xfer->data))
+		return 0;
+
+	if (xfer->rnw)
+		xfer->bounce_buf = kzalloc(xfer->data_len, GFP_KERNEL);
+	else
+		xfer->bounce_buf = kmemdup(xfer->data,
+					   xfer->data_len, GFP_KERNEL);
+
+	return xfer->bounce_buf == NULL ? -ENOMEM : 0;
+}
+
+static void i3c_hci_free_safe_xfer_buf(struct i3c_hci *hci,
+				       struct hci_xfer *xfer)
+{
+	if (hci->io != &mipi_i3c_hci_dma || xfer->bounce_buf == NULL)
+		return;
+
+	if (xfer->rnw)
+		memcpy(xfer->data, xfer->bounce_buf, xfer->data_len);
+
+	kfree(xfer->bounce_buf);
+}
+
 static int i3c_hci_priv_xfers(struct i3c_dev_desc *dev,
 			      struct i3c_priv_xfer *i3c_xfers,
 			      int nxfers)
@@ -302,6 +337,9 @@ static int i3c_hci_priv_xfers(struct i3c_dev_desc *dev,
 		}
 		hci->cmd->prep_i3c_xfer(hci, dev, &xfer[i]);
 		xfer[i].cmd_desc[0] |= CMD_0_ROC;
+		ret = i3c_hci_alloc_safe_xfer_buf(hci, &xfer[i]);
+		if (ret)
+			goto out;
 	}
 	last = i - 1;
 	xfer[last].cmd_desc[0] |= CMD_0_TOC;
@@ -325,6 +363,9 @@ static int i3c_hci_priv_xfers(struct i3c_dev_desc *dev,
 	}
 
 out:
+	for (i = 0; i < nxfers; i++)
+		i3c_hci_free_safe_xfer_buf(hci, &xfer[i]);
+
 	hci_free_xfer(xfer, nxfers);
 	return ret;
 }
@@ -350,6 +391,9 @@ static int i3c_hci_i2c_xfers(struct i2c_dev_desc *dev,
 		xfer[i].rnw = i2c_xfers[i].flags & I2C_M_RD;
 		hci->cmd->prep_i2c_xfer(hci, dev, &xfer[i]);
 		xfer[i].cmd_desc[0] |= CMD_0_ROC;
+		ret = i3c_hci_alloc_safe_xfer_buf(hci, &xfer[i]);
+		if (ret)
+			goto out;
 	}
 	last = i - 1;
 	xfer[last].cmd_desc[0] |= CMD_0_TOC;
@@ -371,6 +415,9 @@ static int i3c_hci_i2c_xfers(struct i2c_dev_desc *dev,
 	}
 
 out:
+	for (i = 0; i < nxfers; i++)
+		i3c_hci_free_safe_xfer_buf(hci, &xfer[i]);
+
 	hci_free_xfer(xfer, nxfers);
 	return ret;
 }

drivers/i3c/master/mipi-i3c-hci/dma.c

@@ -362,6 +362,7 @@ static int hci_dma_queue_xfer(struct i3c_hci *hci,
 	struct hci_rh_data *rh;
 	unsigned int i, ring, enqueue_ptr;
 	u32 op1_val, op2_val;
+	void *buf;
 
 	/* For now we only use ring 0 */
 	ring = 0;
@@ -390,9 +391,10 @@ static int hci_dma_queue_xfer(struct i3c_hci *hci,
 
 		/* 2nd and 3rd words of Data Buffer Descriptor Structure */
 		if (xfer->data) {
+			buf = xfer->bounce_buf ? xfer->bounce_buf : xfer->data;
 			xfer->data_dma =
 				dma_map_single(&hci->master.dev,
-					       xfer->data,
+					       buf,
 					       xfer->data_len,
 					       xfer->rnw ?
 						  DMA_FROM_DEVICE :

drivers/i3c/master/mipi-i3c-hci/hci.h

@@ -90,6 +90,7 @@ struct hci_xfer {
 		struct {
 			/* DMA specific */
 			dma_addr_t data_dma;
+			void *bounce_buf;
 			int ring_number;
 			int ring_entry;
 		};