memory: ti-aemif: Export aemif_*_cs_timings()

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>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20241204094319.1050826-7-bastien.curutchet@bootlin.com
[krzysztof: wrap aemif_set_cs_timings() at 80-char]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Author: bastien-curutchet

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>
@@ -79,26 +81,6 @@
 
 #define CONFIG_MASK	(EW(EW_MAX) | SSTROBE(SSTROBE_MAX) | ASIZE_MAX)
 
-/**
- * struct aemif_cs_timings: structure to hold CS timings
- * @wstrobe: write strobe width, number of cycles - 1
- * @rstrobe: read strobe width, number of cycles - 1
- * @wsetup: write setup width, number of cycles - 1
- * @whold: write hold width, number of cycles - 1
- * @rsetup: read setup width, number of cycles - 1
- * @rhold: read hold width, number of cycles - 1
- * @ta: minimum turn around time, number of cycles - 1
- */
-struct aemif_cs_timings {
-	u32	wstrobe;
-	u32	rstrobe;
-	u32	wsetup;
-	u32	whold;
-	u32	rsetup;
-	u32	rhold;
-	u32	ta;
-};
-
 /**
  * struct aemif_cs_data: structure to hold CS parameters
  * @timings: timings configuration
@@ -123,6 +105,7 @@ struct aemif_cs_data {
  * @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;
@@ -131,6 +114,7 @@ struct aemif_device {
 	u8 num_cs;
 	int cs_offset;
 	struct aemif_cs_data cs_data[NUM_CS];
+	struct mutex config_cs_lock;
 };
 
 /**
@@ -139,7 +123,7 @@ struct aemif_device {
  *
  * @return: 0 if the timing configuration is valid, negative error number 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;
@@ -164,6 +148,7 @@ static int aemif_check_cs_timings(struct aemif_cs_timings *timings)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(aemif_check_cs_timings);
 
 /**
  * aemif_set_cs_timings() - Set the timing configuration of a given chip select.
@@ -173,7 +158,8 @@ 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;
@@ -195,13 +181,16 @@ 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_GPL(aemif_set_cs_timings);
 
 /**
  * aemif_calc_rate - calculate timing data.
@@ -257,10 +246,12 @@ 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, &data->timings);
 }
@@ -399,6 +390,7 @@ 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

include/linux/memory/ti-aemif.h

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __MEMORY_TI_AEMIF_H
+#define __MEMORY_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 // __MEMORY_TI_AEMIF_H