[PATCH v2 1/1] soc: ti: PRUSS OCP configuration

[Basharath Hussain Khaja <basharath@couthit.com>]

From: Roger Quadros <rogerq@ti.com>

Updates OCP master port configuration to enable memory access outside
of the PRU-ICSS subsystem.

This set of changes configures PRUSS_SYSCFG.STANDBY_INIT bit either
to enable or disable the OCP master ports (applicable only on SoCs
using OCP interconnect like the OMAP family).

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Parvathi Pudi <parvathi@couthit.com>
Signed-off-by: Basharath Hussain Khaja <basharath@couthit.com>
---
 drivers/soc/ti/pruss.c       | 77 +++++++++++++++++++++++++++++++++++-
 include/linux/pruss_driver.h |  6 +++
 2 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
index d7634bf5413a..a0e233da052c 100644
--- a/drivers/soc/ti/pruss.c
+++ b/drivers/soc/ti/pruss.c
@@ -25,14 +25,19 @@
 #include <linux/slab.h>
 #include "pruss.h"
 
+#define SYSCFG_STANDBY_INIT	BIT(4)
+#define SYSCFG_SUB_MWAIT_READY	BIT(5)
+
 /**
  * struct pruss_private_data - PRUSS driver private data
  * @has_no_sharedram: flag to indicate the absence of PRUSS Shared Data RAM
  * @has_core_mux_clock: flag to indicate the presence of PRUSS core clock
+ * @has_ocp_syscfg: flag to indicate if OCP SYSCFG is present
  */
 struct pruss_private_data {
 	bool has_no_sharedram;
 	bool has_core_mux_clock;
+	bool has_ocp_syscfg;
 };
 
 /**
@@ -286,6 +291,72 @@ int pruss_cfg_xfr_enable(struct pruss *pruss, enum pru_type pru_type,
 }
 EXPORT_SYMBOL_GPL(pruss_cfg_xfr_enable);
 
+/**
+ * pruss_cfg_ocp_master_ports() - configure PRUSS OCP master ports
+ * @pruss: the pruss instance handle
+ * @enable: set to true for enabling or false for disabling the OCP master ports
+ *
+ * This function programs the PRUSS_SYSCFG.STANDBY_INIT bit either to enable or
+ * disable the OCP master ports (applicable only on SoCs using OCP interconnect
+ * like the OMAP family). Clearing the bit achieves dual functionalities - one
+ * is to deassert the MStandby signal to the device PRCM, and the other is to
+ * enable OCP master ports to allow accesses outside of the PRU-ICSS. The
+ * function has to wait for the PRCM to acknowledge through the monitoring of
+ * the PRUSS_SYSCFG.SUB_MWAIT bit when enabling master ports. Setting the bit
+ * disables the master access, and also signals the PRCM that the PRUSS is ready
+ * for Standby.
+ *
+ * Return: 0 on success, or an error code otherwise. ETIMEDOUT is returned
+ * when the ready-state fails.
+ */
+int pruss_cfg_ocp_master_ports(struct pruss *pruss, bool enable)
+{
+	const struct pruss_private_data *data;
+	u32 syscfg_val, i;
+	int ret;
+
+	if (IS_ERR_OR_NULL(pruss))
+		return -EINVAL;
+
+	data = of_device_get_match_data(pruss->dev);
+
+	/* nothing to do on non OMAP-SoCs */
+	if (!data || !data->has_ocp_syscfg)
+		return 0;
+
+       /* assert the MStandby signal during disable path */
+	if (!enable)
+		return pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG,
+					SYSCFG_STANDBY_INIT,
+					SYSCFG_STANDBY_INIT);
+
+	/* enable the OCP master ports and disable MStandby */
+	ret = pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG, SYSCFG_STANDBY_INIT, 0);
+	if (ret)
+		return ret;
+
+	/* wait till we are ready for transactions - delay is arbitrary */
+	for (i = 0; i < 10; i++) {
+		ret = pruss_cfg_read(pruss, PRUSS_CFG_SYSCFG, &syscfg_val);
+		if (ret)
+			goto disable;
+
+		if (!(syscfg_val & SYSCFG_SUB_MWAIT_READY))
+			return 0;
+
+		udelay(5);
+	}
+
+	dev_err(pruss->dev, "timeout waiting for SUB_MWAIT_READY\n");
+	ret = -ETIMEDOUT;
+
+disable:
+	pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG, SYSCFG_STANDBY_INIT,
+			 SYSCFG_STANDBY_INIT);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pruss_cfg_ocp_master_ports);
+
 static void pruss_of_free_clk_provider(void *data)
 {
 	struct device_node *clk_mux_np = data;
@@ -570,6 +641,10 @@ static const struct pruss_private_data am437x_pruss0_data = {
 	.has_no_sharedram = true,
 };
 
+static const struct pruss_private_data am57xx_data = {
+	.has_ocp_syscfg = true,
+};
+
 static const struct pruss_private_data am65x_j721e_pruss_data = {
 	.has_core_mux_clock = true,
 };
@@ -578,7 +653,7 @@ static const struct of_device_id pruss_of_match[] = {
 	{ .compatible = "ti,am3356-pruss" },
 	{ .compatible = "ti,am4376-pruss0", .data = &am437x_pruss0_data, },
 	{ .compatible = "ti,am4376-pruss1", .data = &am437x_pruss1_data, },
-	{ .compatible = "ti,am5728-pruss" },
+	{ .compatible = "ti,am5728-pruss", .data = &am57xx_data, },
 	{ .compatible = "ti,k2g-pruss" },
 	{ .compatible = "ti,am654-icssg", .data = &am65x_j721e_pruss_data, },
 	{ .compatible = "ti,j721e-icssg", .data = &am65x_j721e_pruss_data, },
diff --git a/include/linux/pruss_driver.h b/include/linux/pruss_driver.h
index 2e18fef1a2e1..15b3c9c58539 100644
--- a/include/linux/pruss_driver.h
+++ b/include/linux/pruss_driver.h
@@ -118,6 +118,7 @@ int pruss_cfg_gpimode(struct pruss *pruss, enum pruss_pru_id pru_id,
 int pruss_cfg_miirt_enable(struct pruss *pruss, bool enable);
 int pruss_cfg_xfr_enable(struct pruss *pruss, enum pru_type pru_type,
 			 bool enable);
+int pruss_cfg_ocp_master_ports(struct pruss *pruss, bool enable);
 
 #else
 
@@ -172,6 +173,11 @@ static inline int pruss_cfg_xfr_enable(struct pruss *pruss,
 	return -EOPNOTSUPP;
 }
 
+static int pruss_cfg_ocp_master_ports(struct pruss *pruss, bool enable)
+{
+	return -EOPNOTSUPP;
+}
+
 #endif /* CONFIG_TI_PRUSS */
 
 #endif	/* _PRUSS_DRIVER_H_ */
-- 
2.34.1