[PATCH v2] memory: tegra: Deduplicate rate request management code

[PATCH v2] memory: tegra: Deduplicate rate request management code

[Mikko Perttunen]

As is, the EMC drivers for each 32-bit platform contain almost
identical duplicated code for aggregating rate requests. Move this
code out to a shared tegra-emc-common file to reduce duplication,
and add kerneldoc comments.

Based on code from the tegra20-emc driver.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
v2:
- Add kerneldoc comments.
- Add note about source of the code to commit message.
- Drop the Tegra114 EMC series as dependency. Rebase on v7.0.
---
 drivers/memory/tegra/Kconfig            |   6 ++
 drivers/memory/tegra/Makefile           |   1 +
 drivers/memory/tegra/tegra-emc-common.c | 139 ++++++++++++++++++++++++++++++++
 drivers/memory/tegra/tegra-emc-common.h |  45 +++++++++++
 drivers/memory/tegra/tegra124-emc.c     | 107 ++----------------------
 drivers/memory/tegra/tegra20-emc.c      | 110 ++-----------------------
 drivers/memory/tegra/tegra30-emc.c      | 107 ++----------------------
 7 files changed, 210 insertions(+), 305 deletions(-)

diff --git a/drivers/memory/tegra/Kconfig b/drivers/memory/tegra/Kconfig
index fc5a27791826..92671f9df672 100644
--- a/drivers/memory/tegra/Kconfig
+++ b/drivers/memory/tegra/Kconfig
@@ -17,6 +17,7 @@ config TEGRA20_EMC
 	select DEVFREQ_GOV_SIMPLE_ONDEMAND
 	select PM_DEVFREQ
 	select DDR
+	select TEGRA_EMC_COMMON
 	help
 	  This driver is for the External Memory Controller (EMC) found on
 	  Tegra20 chips. The EMC controls the external DRAM on the board.
@@ -29,6 +30,7 @@ config TEGRA30_EMC
 	depends on ARCH_TEGRA_3x_SOC || COMPILE_TEST
 	select PM_OPP
 	select DDR
+	select TEGRA_EMC_COMMON
 	help
 	  This driver is for the External Memory Controller (EMC) found on
 	  Tegra30 chips. The EMC controls the external DRAM on the board.
@@ -41,6 +43,7 @@ config TEGRA124_EMC
 	depends on ARCH_TEGRA_124_SOC || COMPILE_TEST
 	select TEGRA124_CLK_EMC if ARCH_TEGRA
 	select PM_OPP
+	select TEGRA_EMC_COMMON
 	help
 	  This driver is for the External Memory Controller (EMC) found on
 	  Tegra124 chips. The EMC controls the external DRAM on the board.
@@ -61,4 +64,7 @@ config TEGRA210_EMC
 	  This driver is required to change memory timings / clock rate for
 	  external memory.
 
+config TEGRA_EMC_COMMON
+	tristate
+
 endif
diff --git a/drivers/memory/tegra/Makefile b/drivers/memory/tegra/Makefile
index 6334601e6120..75ebb4cb4f29 100644
--- a/drivers/memory/tegra/Makefile
+++ b/drivers/memory/tegra/Makefile
@@ -14,6 +14,7 @@ tegra-mc-$(CONFIG_ARCH_TEGRA_264_SOC) += tegra186.o tegra264.o
 
 obj-$(CONFIG_TEGRA_MC) += tegra-mc.o
 
+obj-$(CONFIG_TEGRA_EMC_COMMON) += tegra-emc-common.o
 obj-$(CONFIG_TEGRA20_EMC)  += tegra20-emc.o
 obj-$(CONFIG_TEGRA30_EMC)  += tegra30-emc.o
 obj-$(CONFIG_TEGRA124_EMC) += tegra124-emc.o
diff --git a/drivers/memory/tegra/tegra-emc-common.c b/drivers/memory/tegra/tegra-emc-common.c
new file mode 100644
index 000000000000..2bd766842fa5
--- /dev/null
+++ b/drivers/memory/tegra/tegra-emc-common.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/pm_opp.h>
+
+#include "tegra-emc-common.h"
+
+/**
+ * tegra_emc_rate_requests_init() - Initialize EMC rate request tracking
+ * @reqs: struct tegra_emc_rate_requests to initialize.
+ * @dev: EMC device.
+ *
+ * Initializes the rate request tracking state with default state
+ * (no active requests). Must be called before using @reqs with
+ * other functions.
+ */
+void tegra_emc_rate_requests_init(struct tegra_emc_rate_requests *reqs,
+				  struct device *dev)
+{
+	unsigned int i;
+
+	mutex_init(&reqs->rate_lock);
+	reqs->dev = dev;
+
+	for (i = 0; i < TEGRA_EMC_RATE_TYPE_MAX; i++) {
+		reqs->requested_rate[i].min_rate = 0;
+		reqs->requested_rate[i].max_rate = ULONG_MAX;
+	}
+}
+EXPORT_SYMBOL_GPL(tegra_emc_rate_requests_init);
+
+static int tegra_emc_request_rate(struct tegra_emc_rate_requests *reqs,
+				  unsigned long new_min_rate,
+				  unsigned long new_max_rate,
+				  enum tegra_emc_rate_request_type type)
+{
+	struct tegra_emc_rate_request *req = reqs->requested_rate;
+	unsigned long min_rate = 0, max_rate = ULONG_MAX;
+	unsigned int i;
+	int err;
+
+	/* select minimum and maximum rates among the requested rates */
+	for (i = 0; i < TEGRA_EMC_RATE_TYPE_MAX; i++, req++) {
+		if (i == type) {
+			min_rate = max(new_min_rate, min_rate);
+			max_rate = min(new_max_rate, max_rate);
+		} else {
+			min_rate = max(req->min_rate, min_rate);
+			max_rate = min(req->max_rate, max_rate);
+		}
+	}
+
+	if (min_rate > max_rate) {
+		dev_err_ratelimited(reqs->dev, "%s: type %u: out of range: %lu %lu\n",
+				    __func__, type, min_rate, max_rate);
+		return -ERANGE;
+	}
+
+	/*
+	 * EMC rate-changes should go via OPP API because it manages voltage
+	 * changes.
+	 */
+	err = dev_pm_opp_set_rate(reqs->dev, min_rate);
+	if (err)
+		return err;
+
+	reqs->requested_rate[type].min_rate = new_min_rate;
+	reqs->requested_rate[type].max_rate = new_max_rate;
+
+	return 0;
+}
+
+/**
+ * tegra_emc_set_min_rate() - Update minimum rate request for a request type
+ * @reqs: rate request tracking state
+ * @rate: new minimum rate in Hz requested by @type
+ * @type: type of request
+ *
+ * Records @rate as the new minimum rate request for @type, recalculates target
+ * rate based on all requests and applies new rate through the OPP API.
+ *
+ * Context: Sleeps. Requests to same @reqs are synchronized via mutex.
+ *
+ * Return:
+ * * %0 - success
+ * * %-ERANGE - request would cause minimum rate request to be higher than
+ *              maximum rate request
+ * * other - setting new rate failed
+ */
+int tegra_emc_set_min_rate(struct tegra_emc_rate_requests *reqs,
+			   unsigned long rate,
+			   enum tegra_emc_rate_request_type type)
+{
+	struct tegra_emc_rate_request *req = &reqs->requested_rate[type];
+	int ret;
+
+	mutex_lock(&reqs->rate_lock);
+	ret = tegra_emc_request_rate(reqs, rate, req->max_rate, type);
+	mutex_unlock(&reqs->rate_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tegra_emc_set_min_rate);
+
+/**
+ * tegra_emc_set_max_rate() - Update maximum rate request for a request type
+ * @reqs: rate request tracking state
+ * @rate: new maximum rate in Hz requested by @type
+ * @type: type of request
+ *
+ * Records @rate as the new maximum rate request for @type, recalculates target
+ * rate based on all requests and applies new rate through the OPP API.
+ *
+ * Context: Sleeps. Requests to same @reqs are synchronized via mutex.
+ *
+ * Return:
+ * * %0 - success
+ * * %-ERANGE - request would cause minimum rate request to be higher than
+ *              maximum rate request
+ * * other - setting new rate failed
+ */
+int tegra_emc_set_max_rate(struct tegra_emc_rate_requests *reqs,
+			   unsigned long rate,
+			   enum tegra_emc_rate_request_type type)
+{
+	struct tegra_emc_rate_request *req = &reqs->requested_rate[type];
+	int ret;
+
+	mutex_lock(&reqs->rate_lock);
+	ret = tegra_emc_request_rate(reqs, req->min_rate, rate, type);
+	mutex_unlock(&reqs->rate_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tegra_emc_set_max_rate);
+
+MODULE_DESCRIPTION("NVIDIA Tegra EMC common code");
+MODULE_LICENSE("GPL");
diff --git a/drivers/memory/tegra/tegra-emc-common.h b/drivers/memory/tegra/tegra-emc-common.h
new file mode 100644
index 000000000000..80e26fb13830
--- /dev/null
+++ b/drivers/memory/tegra/tegra-emc-common.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef TEGRA_EMC_COMMON_H
+#define TEGRA_EMC_COMMON_H
+
+#include <linux/device.h>
+#include <linux/mutex.h>
+
+/**
+ * enum tegra_emc_rate_request_type - source of rate request
+ * @TEGRA_EMC_RATE_DEVFREQ: rate requested by devfreq governor
+ * @TEGRA_EMC_RATE_DEBUG: rate requested through debugfs knobs
+ * @TEGRA_EMC_RATE_ICC: rate requested by ICC framework
+ * @TEGRA_EMC_RATE_TYPE_MAX: number of valid request types
+ */
+enum tegra_emc_rate_request_type {
+	TEGRA_EMC_RATE_DEVFREQ,
+	TEGRA_EMC_RATE_DEBUG,
+	TEGRA_EMC_RATE_ICC,
+	TEGRA_EMC_RATE_TYPE_MAX,
+};
+
+struct tegra_emc_rate_request {
+	unsigned long min_rate;
+	unsigned long max_rate;
+};
+
+struct tegra_emc_rate_requests {
+	struct tegra_emc_rate_request requested_rate[TEGRA_EMC_RATE_TYPE_MAX];
+	struct mutex rate_lock;
+	struct device *dev;
+};
+
+void tegra_emc_rate_requests_init(struct tegra_emc_rate_requests *reqs,
+				  struct device *dev);
+
+int tegra_emc_set_min_rate(struct tegra_emc_rate_requests *reqs,
+			   unsigned long rate,
+			   enum tegra_emc_rate_request_type type);
+
+int tegra_emc_set_max_rate(struct tegra_emc_rate_requests *reqs,
+			   unsigned long rate,
+			   enum tegra_emc_rate_request_type type);
+
+#endif /* TEGRA_EMC_COMMON_H */
diff --git a/drivers/memory/tegra/tegra124-emc.c b/drivers/memory/tegra/tegra124-emc.c
index ff26815e51f1..e33eed6f999e 100644
--- a/drivers/memory/tegra/tegra124-emc.c
+++ b/drivers/memory/tegra/tegra124-emc.c
@@ -27,6 +27,7 @@
 #include <soc/tegra/mc.h>
 
 #include "mc.h"
+#include "tegra-emc-common.h"
 
 #define EMC_FBIO_CFG5				0x104
 #define	EMC_FBIO_CFG5_DRAM_TYPE_MASK		0x3
@@ -467,17 +468,6 @@ struct emc_timing {
 	u32 emc_zcal_interval;
 };
 
-enum emc_rate_request_type {
-	EMC_RATE_DEBUG,
-	EMC_RATE_ICC,
-	EMC_RATE_TYPE_MAX,
-};
-
-struct emc_rate_request {
-	unsigned long min_rate;
-	unsigned long max_rate;
-};
-
 struct tegra_emc {
 	struct device *dev;
 
@@ -503,14 +493,7 @@ struct tegra_emc {
 
 	struct icc_provider provider;
 
-	/*
-	 * There are multiple sources in the EMC driver which could request
-	 * a min/max clock rate, these rates are contained in this array.
-	 */
-	struct emc_rate_request requested_rate[EMC_RATE_TYPE_MAX];
-
-	/* protect shared rate-change code path */
-	struct mutex rate_lock;
+	struct tegra_emc_rate_requests reqs;
 };
 
 /* Timing change sequence functions */
@@ -1041,83 +1024,6 @@ tegra124_emc_find_node_by_ram_code(struct device_node *node, u32 ram_code)
 	return NULL;
 }
 
-static void tegra124_emc_rate_requests_init(struct tegra_emc *emc)
-{
-	unsigned int i;
-
-	for (i = 0; i < EMC_RATE_TYPE_MAX; i++) {
-		emc->requested_rate[i].min_rate = 0;
-		emc->requested_rate[i].max_rate = ULONG_MAX;
-	}
-}
-
-static int emc_request_rate(struct tegra_emc *emc,
-			    unsigned long new_min_rate,
-			    unsigned long new_max_rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = emc->requested_rate;
-	unsigned long min_rate = 0, max_rate = ULONG_MAX;
-	unsigned int i;
-	int err;
-
-	/* select minimum and maximum rates among the requested rates */
-	for (i = 0; i < EMC_RATE_TYPE_MAX; i++, req++) {
-		if (i == type) {
-			min_rate = max(new_min_rate, min_rate);
-			max_rate = min(new_max_rate, max_rate);
-		} else {
-			min_rate = max(req->min_rate, min_rate);
-			max_rate = min(req->max_rate, max_rate);
-		}
-	}
-
-	if (min_rate > max_rate) {
-		dev_err_ratelimited(emc->dev, "%s: type %u: out of range: %lu %lu\n",
-				    __func__, type, min_rate, max_rate);
-		return -ERANGE;
-	}
-
-	/*
-	 * EMC rate-changes should go via OPP API because it manages voltage
-	 * changes.
-	 */
-	err = dev_pm_opp_set_rate(emc->dev, min_rate);
-	if (err)
-		return err;
-
-	emc->requested_rate[type].min_rate = new_min_rate;
-	emc->requested_rate[type].max_rate = new_max_rate;
-
-	return 0;
-}
-
-static int emc_set_min_rate(struct tegra_emc *emc, unsigned long rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = &emc->requested_rate[type];
-	int ret;
-
-	mutex_lock(&emc->rate_lock);
-	ret = emc_request_rate(emc, rate, req->max_rate, type);
-	mutex_unlock(&emc->rate_lock);
-
-	return ret;
-}
-
-static int emc_set_max_rate(struct tegra_emc *emc, unsigned long rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = &emc->requested_rate[type];
-	int ret;
-
-	mutex_lock(&emc->rate_lock);
-	ret = emc_request_rate(emc, req->min_rate, rate, type);
-	mutex_unlock(&emc->rate_lock);
-
-	return ret;
-}
-
 /*
  * debugfs interface
  *
@@ -1190,7 +1096,7 @@ static int tegra124_emc_debug_min_rate_set(void *data, u64 rate)
 	if (!tegra124_emc_validate_rate(emc, rate))
 		return -EINVAL;
 
-	err = emc_set_min_rate(emc, rate, EMC_RATE_DEBUG);
+	err = tegra_emc_set_min_rate(&emc->reqs, rate, TEGRA_EMC_RATE_DEBUG);
 	if (err < 0)
 		return err;
 
@@ -1220,7 +1126,7 @@ static int tegra124_emc_debug_max_rate_set(void *data, u64 rate)
 	if (!tegra124_emc_validate_rate(emc, rate))
 		return -EINVAL;
 
-	err = emc_set_max_rate(emc, rate, EMC_RATE_DEBUG);
+	err = tegra_emc_set_max_rate(&emc->reqs, rate, TEGRA_EMC_RATE_DEBUG);
 	if (err < 0)
 		return err;
 
@@ -1327,7 +1233,7 @@ static int emc_icc_set(struct icc_node *src, struct icc_node *dst)
 	do_div(rate, ddr * dram_data_bus_width_bytes);
 	rate = min_t(u64, rate, U32_MAX);
 
-	err = emc_set_min_rate(emc, rate, EMC_RATE_ICC);
+	err = tegra_emc_set_min_rate(&emc->reqs, rate, TEGRA_EMC_RATE_ICC);
 	if (err)
 		return err;
 
@@ -1441,7 +1347,6 @@ static int tegra124_emc_probe(struct platform_device *pdev)
 	if (!emc)
 		return -ENOMEM;
 
-	mutex_init(&emc->rate_lock);
 	emc->dev = &pdev->dev;
 
 	emc->regs = devm_platform_ioremap_resource(pdev, 0);
@@ -1487,7 +1392,7 @@ static int tegra124_emc_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
-	tegra124_emc_rate_requests_init(emc);
+	tegra_emc_rate_requests_init(&emc->reqs, &pdev->dev);
 
 	if (IS_ENABLED(CONFIG_DEBUG_FS))
 		emc_debugfs_init(&pdev->dev, emc);
diff --git a/drivers/memory/tegra/tegra20-emc.c b/drivers/memory/tegra/tegra20-emc.c
index a1fadefee7fd..1d564b80e2bb 100644
--- a/drivers/memory/tegra/tegra20-emc.c
+++ b/drivers/memory/tegra/tegra20-emc.c
@@ -32,6 +32,7 @@
 #include "../of_memory.h"
 
 #include "mc.h"
+#include "tegra-emc-common.h"
 
 #define EMC_INTSTATUS				0x000
 #define EMC_INTMASK				0x004
@@ -182,18 +183,6 @@ struct emc_timing {
 	u32 data[ARRAY_SIZE(emc_timing_registers)];
 };
 
-enum emc_rate_request_type {
-	EMC_RATE_DEVFREQ,
-	EMC_RATE_DEBUG,
-	EMC_RATE_ICC,
-	EMC_RATE_TYPE_MAX,
-};
-
-struct emc_rate_request {
-	unsigned long min_rate;
-	unsigned long max_rate;
-};
-
 struct tegra_emc {
 	struct device *dev;
 	struct tegra_mc *mc;
@@ -212,14 +201,7 @@ struct tegra_emc {
 		unsigned long max_rate;
 	} debugfs;
 
-	/*
-	 * There are multiple sources in the EMC driver which could request
-	 * a min/max clock rate, these rates are contained in this array.
-	 */
-	struct emc_rate_request requested_rate[EMC_RATE_TYPE_MAX];
-
-	/* protect shared rate-change code path */
-	struct mutex rate_lock;
+	struct tegra_emc_rate_requests reqs;
 
 	struct devfreq_simple_ondemand_data ondemand_data;
 
@@ -710,83 +692,6 @@ static long emc_round_rate(unsigned long rate,
 	return timing->rate;
 }
 
-static void tegra20_emc_rate_requests_init(struct tegra_emc *emc)
-{
-	unsigned int i;
-
-	for (i = 0; i < EMC_RATE_TYPE_MAX; i++) {
-		emc->requested_rate[i].min_rate = 0;
-		emc->requested_rate[i].max_rate = ULONG_MAX;
-	}
-}
-
-static int emc_request_rate(struct tegra_emc *emc,
-			    unsigned long new_min_rate,
-			    unsigned long new_max_rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = emc->requested_rate;
-	unsigned long min_rate = 0, max_rate = ULONG_MAX;
-	unsigned int i;
-	int err;
-
-	/* select minimum and maximum rates among the requested rates */
-	for (i = 0; i < EMC_RATE_TYPE_MAX; i++, req++) {
-		if (i == type) {
-			min_rate = max(new_min_rate, min_rate);
-			max_rate = min(new_max_rate, max_rate);
-		} else {
-			min_rate = max(req->min_rate, min_rate);
-			max_rate = min(req->max_rate, max_rate);
-		}
-	}
-
-	if (min_rate > max_rate) {
-		dev_err_ratelimited(emc->dev, "%s: type %u: out of range: %lu %lu\n",
-				    __func__, type, min_rate, max_rate);
-		return -ERANGE;
-	}
-
-	/*
-	 * EMC rate-changes should go via OPP API because it manages voltage
-	 * changes.
-	 */
-	err = dev_pm_opp_set_rate(emc->dev, min_rate);
-	if (err)
-		return err;
-
-	emc->requested_rate[type].min_rate = new_min_rate;
-	emc->requested_rate[type].max_rate = new_max_rate;
-
-	return 0;
-}
-
-static int emc_set_min_rate(struct tegra_emc *emc, unsigned long rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = &emc->requested_rate[type];
-	int ret;
-
-	mutex_lock(&emc->rate_lock);
-	ret = emc_request_rate(emc, rate, req->max_rate, type);
-	mutex_unlock(&emc->rate_lock);
-
-	return ret;
-}
-
-static int emc_set_max_rate(struct tegra_emc *emc, unsigned long rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = &emc->requested_rate[type];
-	int ret;
-
-	mutex_lock(&emc->rate_lock);
-	ret = emc_request_rate(emc, req->min_rate, rate, type);
-	mutex_unlock(&emc->rate_lock);
-
-	return ret;
-}
-
 /*
  * debugfs interface
  *
@@ -857,7 +762,7 @@ static int tegra20_emc_debug_min_rate_set(void *data, u64 rate)
 	if (!tegra20_emc_validate_rate(emc, rate))
 		return -EINVAL;
 
-	err = emc_set_min_rate(emc, rate, EMC_RATE_DEBUG);
+	err = tegra_emc_set_min_rate(&emc->reqs, rate, TEGRA_EMC_RATE_DEBUG);
 	if (err < 0)
 		return err;
 
@@ -887,7 +792,7 @@ static int tegra20_emc_debug_max_rate_set(void *data, u64 rate)
 	if (!tegra20_emc_validate_rate(emc, rate))
 		return -EINVAL;
 
-	err = emc_set_max_rate(emc, rate, EMC_RATE_DEBUG);
+	err = tegra_emc_set_max_rate(&emc->reqs, rate, TEGRA_EMC_RATE_DEBUG);
 	if (err < 0)
 		return err;
 
@@ -993,7 +898,7 @@ static int emc_icc_set(struct icc_node *src, struct icc_node *dst)
 	do_div(rate, dram_data_bus_width_bytes);
 	rate = min_t(u64, rate, U32_MAX);
 
-	err = emc_set_min_rate(emc, rate, EMC_RATE_ICC);
+	err = tegra_emc_set_min_rate(&emc->reqs, rate, TEGRA_EMC_RATE_ICC);
 	if (err)
 		return err;
 
@@ -1111,7 +1016,7 @@ static int tegra20_emc_devfreq_target(struct device *dev, unsigned long *freq,
 	rate = dev_pm_opp_get_freq(opp);
 	dev_pm_opp_put(opp);
 
-	return emc_set_min_rate(emc, rate, EMC_RATE_DEVFREQ);
+	return tegra_emc_set_min_rate(&emc->reqs, rate, TEGRA_EMC_RATE_DEVFREQ);
 }
 
 static int tegra20_emc_devfreq_get_dev_status(struct device *dev,
@@ -1190,7 +1095,6 @@ static int tegra20_emc_probe(struct platform_device *pdev)
 	if (!emc)
 		return -ENOMEM;
 
-	mutex_init(&emc->rate_lock);
 	emc->clk_nb.notifier_call = tegra20_emc_clk_change_notify;
 	emc->dev = &pdev->dev;
 
@@ -1228,7 +1132,7 @@ static int tegra20_emc_probe(struct platform_device *pdev)
 		return err;
 
 	platform_set_drvdata(pdev, emc);
-	tegra20_emc_rate_requests_init(emc);
+	tegra_emc_rate_requests_init(&emc->reqs, &pdev->dev);
 	tegra20_emc_debugfs_init(emc);
 	tegra20_emc_interconnect_init(emc);
 	tegra20_emc_devfreq_init(emc);
diff --git a/drivers/memory/tegra/tegra30-emc.c b/drivers/memory/tegra/tegra30-emc.c
index 606106dd2b32..afd272da0d27 100644
--- a/drivers/memory/tegra/tegra30-emc.c
+++ b/drivers/memory/tegra/tegra30-emc.c
@@ -36,6 +36,7 @@
 #include "../of_memory.h"
 
 #include "mc.h"
+#include "tegra-emc-common.h"
 
 #define EMC_INTSTATUS				0x000
 #define EMC_INTMASK				0x004
@@ -341,17 +342,6 @@ struct emc_timing {
 	bool emc_cfg_dyn_self_ref;
 };
 
-enum emc_rate_request_type {
-	EMC_RATE_DEBUG,
-	EMC_RATE_ICC,
-	EMC_RATE_TYPE_MAX,
-};
-
-struct emc_rate_request {
-	unsigned long min_rate;
-	unsigned long max_rate;
-};
-
 struct tegra_emc {
 	struct device *dev;
 	struct tegra_mc *mc;
@@ -383,14 +373,7 @@ struct tegra_emc {
 		unsigned long max_rate;
 	} debugfs;
 
-	/*
-	 * There are multiple sources in the EMC driver which could request
-	 * a min/max clock rate, these rates are contained in this array.
-	 */
-	struct emc_rate_request requested_rate[EMC_RATE_TYPE_MAX];
-
-	/* protect shared rate-change code path */
-	struct mutex rate_lock;
+	struct tegra_emc_rate_requests reqs;
 
 	bool mrr_error;
 };
@@ -1228,83 +1211,6 @@ static long emc_round_rate(unsigned long rate,
 	return timing->rate;
 }
 
-static void tegra30_emc_rate_requests_init(struct tegra_emc *emc)
-{
-	unsigned int i;
-
-	for (i = 0; i < EMC_RATE_TYPE_MAX; i++) {
-		emc->requested_rate[i].min_rate = 0;
-		emc->requested_rate[i].max_rate = ULONG_MAX;
-	}
-}
-
-static int emc_request_rate(struct tegra_emc *emc,
-			    unsigned long new_min_rate,
-			    unsigned long new_max_rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = emc->requested_rate;
-	unsigned long min_rate = 0, max_rate = ULONG_MAX;
-	unsigned int i;
-	int err;
-
-	/* select minimum and maximum rates among the requested rates */
-	for (i = 0; i < EMC_RATE_TYPE_MAX; i++, req++) {
-		if (i == type) {
-			min_rate = max(new_min_rate, min_rate);
-			max_rate = min(new_max_rate, max_rate);
-		} else {
-			min_rate = max(req->min_rate, min_rate);
-			max_rate = min(req->max_rate, max_rate);
-		}
-	}
-
-	if (min_rate > max_rate) {
-		dev_err_ratelimited(emc->dev, "%s: type %u: out of range: %lu %lu\n",
-				    __func__, type, min_rate, max_rate);
-		return -ERANGE;
-	}
-
-	/*
-	 * EMC rate-changes should go via OPP API because it manages voltage
-	 * changes.
-	 */
-	err = dev_pm_opp_set_rate(emc->dev, min_rate);
-	if (err)
-		return err;
-
-	emc->requested_rate[type].min_rate = new_min_rate;
-	emc->requested_rate[type].max_rate = new_max_rate;
-
-	return 0;
-}
-
-static int emc_set_min_rate(struct tegra_emc *emc, unsigned long rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = &emc->requested_rate[type];
-	int ret;
-
-	mutex_lock(&emc->rate_lock);
-	ret = emc_request_rate(emc, rate, req->max_rate, type);
-	mutex_unlock(&emc->rate_lock);
-
-	return ret;
-}
-
-static int emc_set_max_rate(struct tegra_emc *emc, unsigned long rate,
-			    enum emc_rate_request_type type)
-{
-	struct emc_rate_request *req = &emc->requested_rate[type];
-	int ret;
-
-	mutex_lock(&emc->rate_lock);
-	ret = emc_request_rate(emc, req->min_rate, rate, type);
-	mutex_unlock(&emc->rate_lock);
-
-	return ret;
-}
-
 /*
  * debugfs interface
  *
@@ -1375,7 +1281,7 @@ static int tegra30_emc_debug_min_rate_set(void *data, u64 rate)
 	if (!tegra30_emc_validate_rate(emc, rate))
 		return -EINVAL;
 
-	err = emc_set_min_rate(emc, rate, EMC_RATE_DEBUG);
+	err = tegra_emc_set_min_rate(&emc->reqs, rate, TEGRA_EMC_RATE_DEBUG);
 	if (err < 0)
 		return err;
 
@@ -1405,7 +1311,7 @@ static int tegra30_emc_debug_max_rate_set(void *data, u64 rate)
 	if (!tegra30_emc_validate_rate(emc, rate))
 		return -EINVAL;
 
-	err = emc_set_max_rate(emc, rate, EMC_RATE_DEBUG);
+	err = tegra_emc_set_max_rate(&emc->reqs, rate, TEGRA_EMC_RATE_DEBUG);
 	if (err < 0)
 		return err;
 
@@ -1511,7 +1417,7 @@ static int emc_icc_set(struct icc_node *src, struct icc_node *dst)
 	do_div(rate, ddr * dram_data_bus_width_bytes);
 	rate = min_t(u64, rate, U32_MAX);
 
-	err = emc_set_min_rate(emc, rate, EMC_RATE_ICC);
+	err = tegra_emc_set_min_rate(&emc->reqs, rate, TEGRA_EMC_RATE_ICC);
 	if (err)
 		return err;
 
@@ -1622,7 +1528,6 @@ static int tegra30_emc_probe(struct platform_device *pdev)
 	if (IS_ERR(emc->mc))
 		return PTR_ERR(emc->mc);
 
-	mutex_init(&emc->rate_lock);
 	emc->clk_nb.notifier_call = emc_clk_change_notify;
 	emc->dev = &pdev->dev;
 
@@ -1664,7 +1569,7 @@ static int tegra30_emc_probe(struct platform_device *pdev)
 		return err;
 
 	platform_set_drvdata(pdev, emc);
-	tegra30_emc_rate_requests_init(emc);
+	tegra_emc_rate_requests_init(&emc->reqs, &pdev->dev);
 	tegra30_emc_debugfs_init(emc);
 	tegra30_emc_interconnect_init(emc);
 

---
base-commit: 028ef9c96e96197026887c0f092424679298aae8
change-id: 20260203-memory-refactor-54a6089a8dcf

Re: [PATCH v2] memory: tegra: Deduplicate rate request management code

[Krzysztof Kozlowski]

On 17/04/2026 11:19, Mikko Perttunen wrote:
> +
> +struct tegra_emc_rate_request {
> +	unsigned long min_rate;
> +	unsigned long max_rate;
> +};
> +
> +struct tegra_emc_rate_requests {
> +	struct tegra_emc_rate_request requested_rate[TEGRA_EMC_RATE_TYPE_MAX];
> +	struct mutex rate_lock;

You introduced a new checkpatch warning. Wasn't there before. Probably
the old comment feels to obvious in this context, so it should be
extended to be meaningful, e.g. what data structure, which members,
which code paths etc.

Best regards,
Krzysztof

Re: [PATCH v2] memory: tegra: Deduplicate rate request management code

[Mikko Perttunen]

On Tuesday, April 28, 2026 6:12 PM Krzysztof Kozlowski wrote:
> On 17/04/2026 11:19, Mikko Perttunen wrote:
> > +
> > +struct tegra_emc_rate_request {
> > +	unsigned long min_rate;
> > +	unsigned long max_rate;
> > +};
> > +
> > +struct tegra_emc_rate_requests {
> > +	struct tegra_emc_rate_request requested_rate[TEGRA_EMC_RATE_TYPE_MAX];
> > +	struct mutex rate_lock;
> 
> You introduced a new checkpatch warning. Wasn't there before. Probably
> the old comment feels to obvious in this context, so it should be
> extended to be meaningful, e.g. what data structure, which members,
> which code paths etc.

On my system, it's just a 'CHECK', not a 'WARNING', so I thought it
not necessary to address in this relatively simple circumstance.

However, I do agree it's best to err on the side of verbosity when
dealing with locking, so I'll add a description for v3.

Mikko

> 
> Best regards,
> Krzysztof
> 

Re: [PATCH v2] memory: tegra: Deduplicate rate request management code

[Krzysztof Kozlowski]

On 30/04/2026 08:52, Mikko Perttunen wrote:
> On Tuesday, April 28, 2026 6:12 PM Krzysztof Kozlowski wrote:
>> On 17/04/2026 11:19, Mikko Perttunen wrote:
>>> +
>>> +struct tegra_emc_rate_request {
>>> +	unsigned long min_rate;
>>> +	unsigned long max_rate;
>>> +};
>>> +
>>> +struct tegra_emc_rate_requests {
>>> +	struct tegra_emc_rate_request requested_rate[TEGRA_EMC_RATE_TYPE_MAX];
>>> +	struct mutex rate_lock;
>>
>> You introduced a new checkpatch warning. Wasn't there before. Probably
>> the old comment feels to obvious in this context, so it should be
>> extended to be meaningful, e.g. what data structure, which members,
>> which code paths etc.
> 
> On my system, it's just a 'CHECK', not a 'WARNING', so I thought it
> not necessary to address in this relatively simple circumstance.
> 
> However, I do agree it's best to err on the side of verbosity when
> dealing with locking, so I'll add a description for v3.

It's still a warning both in CI and maintainer commit tools. The meaning
of "CHECK" means only amount of false positives, so you are supposed to
check it. And if you checked it you would see it is valid report.

Best regards,
Krzysztof