[RFC PATCH v2] soc: qcom: rmtfs_mem: Control remoteproc from rmtfs_mem

[Sibi Sankar]

From: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>

rmtfs_mem provides access to physical storage and is crucial for the
operation of the Qualcomm modem subsystem.

The rmtfs_mem implementation must be available before the modem
subsystem is booted and a solution where the modem remoteproc will
verify that the rmtfs_mem is available has been discussed in the past.
But this would not handle the case where the rmtfs_mem provider is
restarted, which would cause fatal loss of access to the storage device
for the modem.

The suggestion is therefore to link the rmtfs_mem to its associated
remote processor instance and control it based on the availability of
the rmtfs_mem implementation.

Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
[sibis: Added qmi lookup for Remote file system service]
Signed-off-by: Sibi Sankar <sibis@xxxxxxxxxxxxxx>
---

The currently implemented workaround in the Linaro QCOMLT releases is to
blacklist the qcom_q6v5_pil kernel module and load this explicitly after rmtfs
has been started.

With this patch the modem module can be loaded automatically by the
platform_bus and will only be booted as the rmtfs becomes available. Performing
actions such as upgrading (and restarting) the rmtfs service will cause the
modem to automatically restart and hence continue to function after the
upgrade.

v2:
  Remove rproc_boot/shutdown from rmtfs_mem open/release and add
  qmi lookup for Remote file system service to address Brian's
  race concerns.

 .../reserved-memory/qcom,rmtfs-mem.txt        |  7 ++
 drivers/remoteproc/qcom_q6v5_pil.c            |  1 +
 drivers/soc/qcom/Kconfig                      |  2 +
 drivers/soc/qcom/rmtfs_mem.c                  | 65 ++++++++++++++++++-
 4 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.txt b/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.txt
index 8562ba1dce69..95b209e7f5d1 100644
--- a/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.txt
+++ b/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.txt
@@ -32,6 +32,13 @@ access block device data using the Remote Filesystem protocol.
 	Value type: <u32>
 	Definition: vmid of the remote processor, to set up memory protection.
 
+- rproc:
+	Usage: optional
+	Value type: <phandle>
+	Definition: reference to a remoteproc node, that should be powered up
+		    while the remote file system memory instance is ready to
+		    handle requests from the remote subsystem.
+
 = EXAMPLE
 The following example shows the remote filesystem memory setup for APQ8016,
 with the rmtfs region for the Hexagon DSP (id #1) located at 0x86700000.
diff --git a/drivers/remoteproc/qcom_q6v5_pil.c b/drivers/remoteproc/qcom_q6v5_pil.c
index d7a4b9eca5d2..1445a38e8b34 100644
--- a/drivers/remoteproc/qcom_q6v5_pil.c
+++ b/drivers/remoteproc/qcom_q6v5_pil.c
@@ -1142,6 +1142,7 @@ static int q6v5_probe(struct platform_device *pdev)
 	qproc = (struct q6v5 *)rproc->priv;
 	qproc->dev = &pdev->dev;
 	qproc->rproc = rproc;
+	rproc->auto_boot = false;
 	platform_set_drvdata(pdev, qproc);
 
 	ret = q6v5_init_mem(qproc, pdev);
diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 8a7b8dea6990..4e3345944325 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -86,7 +86,9 @@ config QCOM_QMI_HELPERS
 config QCOM_RMTFS_MEM
 	tristate "Qualcomm Remote Filesystem memory driver"
 	depends on ARCH_QCOM
+	depends on REMOTEPROC
 	select QCOM_SCM
+	select QCOM_QMI_HELPERS
 	help
 	  The Qualcomm remote filesystem memory driver is used for allocating
 	  and exposing regions of shared memory with remote processors for the
diff --git a/drivers/soc/qcom/rmtfs_mem.c b/drivers/soc/qcom/rmtfs_mem.c
index 97bb5989aa21..757e30083f67 100644
--- a/drivers/soc/qcom/rmtfs_mem.c
+++ b/drivers/soc/qcom/rmtfs_mem.c
@@ -18,11 +18,13 @@
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_reserved_mem.h>
+#include <linux/remoteproc.h>
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/qcom_scm.h>
+#include <linux/soc/qcom/qmi.h>
 
 #define QCOM_RMTFS_MEM_DEV_MAX	(MINORMASK + 1)
 
@@ -31,6 +33,7 @@ static dev_t qcom_rmtfs_mem_major;
 struct qcom_rmtfs_mem {
 	struct device dev;
 	struct cdev cdev;
+	struct qmi_handle rmtfs_hdl;
 
 	void *base;
 	phys_addr_t addr;
@@ -39,6 +42,8 @@ struct qcom_rmtfs_mem {
 	unsigned int client_id;
 
 	unsigned int perms;
+
+	struct rproc *rproc;
 };
 
 static ssize_t qcom_rmtfs_mem_show(struct device *dev,
@@ -141,6 +146,36 @@ static const struct file_operations qcom_rmtfs_mem_fops = {
 	.llseek = default_llseek,
 };
 
+static int rmtfs_new_server(struct qmi_handle *qmi,
+				 struct qmi_service *service)
+{
+	int ret = 0;
+	struct qcom_rmtfs_mem *rmtfs_mem = container_of(qmi,
+							struct qcom_rmtfs_mem,
+							rmtfs_hdl);
+
+	if (rmtfs_mem->rproc)
+		ret = rproc_boot(rmtfs_mem->rproc);
+
+	return ret;
+};
+
+static void rmtfs_del_server(struct qmi_handle *qmi,
+				  struct qmi_service *service)
+{
+	struct qcom_rmtfs_mem *rmtfs_mem = container_of(qmi,
+							struct qcom_rmtfs_mem,
+							rmtfs_hdl);
+
+	if (rmtfs_mem->rproc)
+		rproc_shutdown(rmtfs_mem->rproc);
+};
+
+static struct qmi_ops rmtfs_lookup_ops = {
+	.new_server = rmtfs_new_server,
+	.del_server = rmtfs_del_server,
+};
+
 static void qcom_rmtfs_mem_release_device(struct device *dev)
 {
 	struct qcom_rmtfs_mem *rmtfs_mem = container_of(dev,
@@ -156,6 +191,7 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
 	struct qcom_scm_vmperm perms[2];
 	struct reserved_mem *rmem;
 	struct qcom_rmtfs_mem *rmtfs_mem;
+	phandle rproc_phandle;
 	u32 client_id;
 	u32 vmid;
 	int ret;
@@ -181,6 +217,22 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
 	rmtfs_mem->client_id = client_id;
 	rmtfs_mem->size = rmem->size;
 
+	ret = of_property_read_u32(node, "rproc", &rproc_phandle);
+	if (!ret) {
+		rmtfs_mem->rproc = rproc_get_by_phandle(rproc_phandle);
+		if (!rmtfs_mem->rproc)
+			return -EPROBE_DEFER;
+	}
+
+	ret = qmi_handle_init(&rmtfs_mem->rmtfs_hdl, 0,
+			      &rmtfs_lookup_ops, NULL);
+	if (ret < 0)
+		goto put_rproc;
+
+	ret = qmi_add_lookup(&rmtfs_mem->rmtfs_hdl, 14, 0, 0);
+	if (ret < 0)
+		goto err_release_qmi_handle;
+
 	device_initialize(&rmtfs_mem->dev);
 	rmtfs_mem->dev.parent = &pdev->dev;
 	rmtfs_mem->dev.groups = qcom_rmtfs_mem_groups;
@@ -191,7 +243,7 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
 	if (IS_ERR(rmtfs_mem->base)) {
 		dev_err(&pdev->dev, "failed to remap rmtfs_mem region\n");
 		ret = PTR_ERR(rmtfs_mem->base);
-		goto put_device;
+		goto err_release_qmi_handle;
 	}
 
 	cdev_init(&rmtfs_mem->cdev, &qcom_rmtfs_mem_fops);
@@ -204,7 +256,7 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
 	ret = cdev_device_add(&rmtfs_mem->cdev, &rmtfs_mem->dev);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to add cdev: %d\n", ret);
-		goto put_device;
+		goto err_release_qmi_handle;
 	}
 
 	ret = of_property_read_u32(node, "qcom,vmid", &vmid);
@@ -237,7 +289,10 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
 
 remove_cdev:
 	cdev_device_del(&rmtfs_mem->cdev, &rmtfs_mem->dev);
-put_device:
+err_release_qmi_handle:
+	qmi_handle_release(&rmtfs_mem->rmtfs_hdl);
+put_rproc:
+	rproc_put(rmtfs_mem->rproc);
 	put_device(&rmtfs_mem->dev);
 
 	return ret;
@@ -257,6 +312,10 @@ static int qcom_rmtfs_mem_remove(struct platform_device *pdev)
 	}
 
 	cdev_device_del(&rmtfs_mem->cdev, &rmtfs_mem->dev);
+	if (rmtfs_mem->rproc) {
+		qmi_handle_release(&rmtfs_mem->rmtfs_hdl);
+		rproc_put(rmtfs_mem->rproc);
+	}
 	put_device(&rmtfs_mem->dev);
 
 	return 0;
-- 
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