Export the aemif_set_cs_timing() and aemif_check_cs_timing() symbols so
they can be used by other drivers

Add a mutex to protect the CS configuration register from concurrent
accesses between the AEMIF and its 'children'.

Signed-off-by: Bastien Curutchet <bastien.curutchet@bootlin.com>
---
 drivers/memory/ti-aemif.c       | 36 ++++++++++++---------------------
 include/linux/memory/ti-aemif.h | 32 +++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 23 deletions(-)
 create mode 100644 include/linux/memory/ti-aemif.h

diff --git a/drivers/memory/ti-aemif.c b/drivers/memory/ti-aemif.c
index b1236cc9ce92..7f0ca256db3c 100644
--- a/drivers/memory/ti-aemif.c
+++ b/drivers/memory/ti-aemif.c
@@ -13,7 +13,9 @@
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/memory/ti-aemif.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
@@ -107,27 +109,6 @@ struct aemif_cs_data {
 	u8	asize;
 };
 
-/**
- * struct aemif_cs_timings: structure to hold CS timing configuration
- * values are expressed in number of clock cycles - 1
- * @ta: minimum turn around time
- * @rhold: read hold width
- * @rstrobe: read strobe width
- * @rsetup: read setup width
- * @whold: write hold width
- * @wstrobe: write strobe width
- * @wsetup: write setup width
- */
-struct aemif_cs_timings {
-	u32	ta;
-	u32	rhold;
-	u32	rstrobe;
-	u32	rsetup;
-	u32	whold;
-	u32	wstrobe;
-	u32	wsetup;
-};
-
 /**
  * struct aemif_device: structure to hold device data
  * @base: base address of AEMIF registers
@@ -136,6 +117,7 @@ struct aemif_cs_timings {
  * @num_cs: number of assigned chip-selects
  * @cs_offset: start number of cs nodes
  * @cs_data: array of chip-select settings
+ * @config_cs_lock: lock used to access CS configuration
  */
 struct aemif_device {
 	void __iomem *base;
@@ -144,6 +126,7 @@ struct aemif_device {
 	u8 num_cs;
 	int cs_offset;
 	struct aemif_cs_data cs_data[NUM_CS];
+	struct mutex config_cs_lock;
 };
 
 /**
@@ -152,7 +135,7 @@ struct aemif_device {
  *
  * @return: 0 if the timing configuration is valid, negative errno otherwise.
  */
-static int aemif_check_cs_timings(struct aemif_cs_timings *timings)
+int aemif_check_cs_timings(struct aemif_cs_timings *timings)
 {
 	if (timings->ta > TA_MAX)
 		return -EINVAL;
@@ -177,6 +160,7 @@ static int aemif_check_cs_timings(struct aemif_cs_timings *timings)
 
 	return 0;
 }
+EXPORT_SYMBOL(aemif_check_cs_timings);
 
 /**
  * aemif_set_cs_timings - Set the timing configuration of a given chip select.
@@ -186,7 +170,7 @@ static int aemif_check_cs_timings(struct aemif_cs_timings *timings)
  *
  * @return: 0 on success, else negative errno.
  */
-static int aemif_set_cs_timings(struct aemif_device *aemif, u8 cs, struct aemif_cs_timings *timings)
+int aemif_set_cs_timings(struct aemif_device *aemif, u8 cs, struct aemif_cs_timings *timings)
 {
 	unsigned int offset;
 	u32 val, set;
@@ -208,13 +192,16 @@ static int aemif_set_cs_timings(struct aemif_device *aemif, u8 cs, struct aemif_
 
 	offset = A1CR_OFFSET + cs * 4;
 
+	mutex_lock(&aemif->config_cs_lock);
 	val = readl(aemif->base + offset);
 	val &= ~TIMINGS_MASK;
 	val |= set;
 	writel(val, aemif->base + offset);
+	mutex_unlock(&aemif->config_cs_lock);
 
 	return 0;
 }
+EXPORT_SYMBOL(aemif_set_cs_timings);
 
 /**
  * aemif_calc_rate - calculate timing data.
@@ -288,10 +275,12 @@ static int aemif_config_abus(struct platform_device *pdev, int csnum)
 	if (data->enable_ss)
 		set |= ACR_SSTROBE_MASK;
 
+	mutex_lock(&aemif->config_cs_lock);
 	val = readl(aemif->base + offset);
 	val &= ~CONFIG_MASK;
 	val |= set;
 	writel(val, aemif->base + offset);
+	mutex_unlock(&aemif->config_cs_lock);
 
 	return aemif_set_cs_timings(aemif, data->cs - aemif->cs_offset, &timings);
 }
@@ -434,6 +423,7 @@ static int aemif_probe(struct platform_device *pdev)
 	if (IS_ERR(aemif->base))
 		return PTR_ERR(aemif->base);
 
+	mutex_init(&aemif->config_cs_lock);
 	if (np) {
 		/*
 		 * For every controller device node, there is a cs device node
diff --git a/include/linux/memory/ti-aemif.h b/include/linux/memory/ti-aemif.h
new file mode 100644
index 000000000000..0640d30f6321
--- /dev/null
+++ b/include/linux/memory/ti-aemif.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __TI_AEMIF_H
+#define __TI_AEMIF_H
+
+/**
+ * struct aemif_cs_timings: structure to hold CS timing configuration
+ * values are expressed in number of clock cycles - 1
+ * @ta: minimum turn around time
+ * @rhold: read hold width
+ * @rstrobe: read strobe width
+ * @rsetup: read setup width
+ * @whold: write hold width
+ * @wstrobe: write strobe width
+ * @wsetup: write setup width
+ */
+struct aemif_cs_timings {
+	u32	ta;
+	u32	rhold;
+	u32	rstrobe;
+	u32	rsetup;
+	u32	whold;
+	u32	wstrobe;
+	u32	wsetup;
+};
+
+struct aemif_device;
+
+int aemif_set_cs_timings(struct aemif_device *aemif, u8 cs, struct aemif_cs_timings *timings);
+int aemif_check_cs_timings(struct aemif_cs_timings *timings);
+
+#endif // __TI_AEMIF_H
-- 
2.47.0

On 13/11/2024 at 10:49:34 +01, Bastien Curutchet <bastien.curutchet@bootlin.com> wrote:

> Export the aemif_set_cs_timing() and aemif_check_cs_timing() symbols so
> they can be used by other drivers
>
> Add a mutex to protect the CS configuration register from concurrent
> accesses between the AEMIF and its 'children'.

I'll let Krzysztof judge whether it is okay to use EXPORT_SYMBOL instead
of EXPORT_SYMBOL_GPL here, but otherwise looks ok to me.

Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>