[PATCH 09/16] remoteproc/pru: add APIs to get and put the PRU cores

Roger Quadros
2018-11-26T07:52:42Z

From: Tero Kristo <t-kristo@ti.com>

Add two new APIs, pru_rproc_get() and pru_rproc_put(), to the PRU
driver to allow client drivers to acquire and release the remoteproc
device associated with a PRU core. The PRU cores are treated as
resources with only one client owning it at a time.

The pru_rproc_get() function returns the rproc handle corresponding
to a PRU core identified by the device tree "prus" property under
the client node. The pru_rproc_put() is the complementary function
to pru_rproc_get().

Signed-off-by: Tero Kristo <t-kristo@ti.com>
[s-anna@ti.com: improve error checking, various fixes and cleanups]
Signed-off-by: Suman Anna <s-anna@ti.com>
---
drivers/remoteproc/pru_rproc.c | 112 +++++++++++++++++++++++++++++++++++++++++
include/linux/pruss.h | 9 ++++
2 files changed, 121 insertions(+)

diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
index fa3559b..2aa05b0 100644
--- a/drivers/remoteproc/pru_rproc.c
+++ b/drivers/remoteproc/pru_rproc.c
@@ -57,6 +57,7 @@ enum pru_mem {
* @id: id of the PRU core within the PRUSS
* @pruss: back-reference to parent PRUSS structure
* @rproc: remoteproc pointer for this PRU core
+ * @client_np: client device node
* @mbox: mailbox channel handle used for vring signalling with MPU
* @client: mailbox client to request the mailbox channel
* @irq_ring: IRQ number to use for processing vring buffers
@@ -71,6 +72,7 @@ enum pru_mem {
* @sdram_da: device address of secondary Data RAM for this PRU
* @shrdram_da: device address of shared Data RAM
* @fw_name: name of firmware image used during loading
+ * @lock: mutex to protect client usage
* @dbg_single_step: debug state variable to set PRU into single step mode
* @dbg_continuous: debug state variable to restore PRU execution mode
*/
@@ -78,6 +80,7 @@ struct pru_rproc {
int id;
struct pruss *pruss;
struct rproc *rproc;
+ struct device_node *client_np;
struct mbox_chan *mbox;
struct mbox_client client;
int irq_vring;
@@ -92,6 +95,7 @@ struct pru_rproc {
u32 sdram_da;
u32 shrdram_da;
const char *fw_name;
+ struct mutex lock; /* client access lock */
u32 dbg_single_step;
u32 dbg_continuous;
};
@@ -126,6 +130,113 @@ void pru_control_set_reg(struct pru_rproc *pru, unsigned int reg,
spin_unlock_irqrestore(&pru->rmw_lock, flags);
}

+static struct rproc *__pru_rproc_get(struct device_node *np, int index)
+{
+ struct device_node *rproc_np = NULL;
+ struct platform_device *pdev;
+ struct rproc *rproc;
+
+ rproc_np = of_parse_phandle(np, "prus", index);
+ if (!rproc_np || !of_device_is_available(rproc_np))
+ return ERR_PTR(-ENODEV);
+
+ pdev = of_find_device_by_node(rproc_np);
+ of_node_put(rproc_np);
+
+ if (!pdev)
+ /* probably PRU not yet probed */
+ return ERR_PTR(-EPROBE_DEFER);
+
+ /* TODO: replace the crude string based check to make sure it is PRU */
+ if (!strstr(dev_name(&pdev->dev), "pru")) {
+ put_device(&pdev->dev);
+ return ERR_PTR(-ENODEV);
+ }
+
+ rproc = platform_get_drvdata(pdev);
+ put_device(&pdev->dev);
+ if (!rproc)
+ return ERR_PTR(-EPROBE_DEFER);
+
+ get_device(&rproc->dev);
+
+ return rproc;
+}
+
+/**
+ * pru_rproc_get() - get the PRU rproc instance from a device node
+ * @np: the user/client device node
+ * @index: index to use for the prus property
+ *
+ * This function looks through a client device node's "prus" property at index
+ * @index and returns the rproc handle for a valid PRU remote processor if
+ * found. The function allows only one user to own the PRU rproc resource at
+ * a time. Caller must call pru_rproc_put() when done with using the rproc,
+ * not required if the function returns a failure.
+ *
+ * Returns the rproc handle on success, and an ERR_PTR on failure using one
+ * of the following error values
+ * -ENODEV if device is not found
+ * -EBUSY if PRU is already acquired by anyone
+ * -EPROBE_DEFER is PRU device is not probed yet
+ */
+struct rproc *pru_rproc_get(struct device_node *np, int index)
+{
+ struct rproc *rproc;
+ struct pru_rproc *pru;
+
+ rproc = __pru_rproc_get(np, index);
+ if (IS_ERR(rproc))
+ return rproc;
+
+ pru = rproc->priv;
+
+ mutex_lock(&pru->lock);
+
+ if (pru->client_np) {
+ mutex_unlock(&pru->lock);
+ put_device(&rproc->dev);
+ return ERR_PTR(-EBUSY);
+ }
+
+ pru->client_np = np;
+
+ mutex_unlock(&pru->lock);
+
+ return rproc;
+}
+EXPORT_SYMBOL_GPL(pru_rproc_get);
+
+/**
+ * pru_rproc_put() - release the PRU rproc resource
+ * @rproc: the rproc resource to release
+ *
+ * Releases the PRU rproc resource and makes it available to other
+ * users.
+ */
+void pru_rproc_put(struct rproc *rproc)
+{
+ struct pru_rproc *pru;
+
+ if (IS_ERR_OR_NULL(rproc))
+ return;
+
+ /* TODO: replace the crude string based check to make sure it is PRU */
+ if (!strstr(dev_name(rproc->dev.parent), "pru"))
+ return;
+
+ pru = rproc->priv;
+ if (!pru->client_np)
+ return;
+
+ mutex_lock(&pru->lock);
+ pru->client_np = NULL;
+ mutex_unlock(&pru->lock);
+
+ put_device(&rproc->dev);
+}
+EXPORT_SYMBOL_GPL(pru_rproc_put);
+
/**
* pru_rproc_set_ctable() - set the constant table index for the PRU
* @rproc: the rproc instance of the PRU
@@ -588,6 +699,7 @@ static int pru_rproc_probe(struct platform_device *pdev)
pru->rproc = rproc;
pru->fw_name = fw_name;
spin_lock_init(&pru->rmw_lock);
+ mutex_init(&pru->lock);

ret = pruss_request_mem_region(pru->pruss, PRUSS_MEM_DRAM0,
&pru->dram0);
diff --git a/include/linux/pruss.h b/include/linux/pruss.h
index af04a1c..405039a 100644
--- a/include/linux/pruss.h
+++ b/include/linux/pruss.h
@@ -249,10 +249,19 @@ int pruss_intc_unconfigure(struct pruss *pruss,

#if IS_ENABLED(CONFIG_PRUSS_REMOTEPROC)

+struct rproc *pru_rproc_get(struct device_node *node, int index);
+void pru_rproc_put(struct rproc *rproc);
int pru_rproc_set_ctable(struct rproc *rproc, enum pru_ctable_idx c, u32 addr);

#else

+static inline struct rproc *pru_rproc_get(struct device_node *node, int index)
+{
+ return ERR_PTR(-ENOTSUPP);
+}
+
+static inline void pru_rproc_put(struct rproc *rproc) { }
+
static inline int pru_rproc_set_ctable(struct rproc *rproc,
enum pru_ctable_idx c, u32 addr)
{