* [PATCH v4] soc: at91: Add Atmel SFR SN (Serial Number) support
@ 2019-10-04 12:24 Kamel Bouhara
2019-10-04 14:12 ` Tudor.Ambarus
0 siblings, 1 reply; 2+ messages in thread
From: Kamel Bouhara @ 2019-10-04 12:24 UTC (permalink / raw)
To: Nicolas Ferre, Alexandre Belloni, Ludovic Desroches, linux-arm-kernel
Cc: Kamel Bouhara, Thomas Petazzoni
Add support to read SFR's read-only registers providing the SoC
Serial Numbers (SN0+SN1) to userspace.
~ # hexdump -n 8 -e'"%d\n"' /sys/bus/nvmem/devices/atmel-sfr0/nvmem
959527243
371539274
Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
---
drivers/soc/atmel/Kconfig | 11 ++++
drivers/soc/atmel/Makefile | 1 +
drivers/soc/atmel/sfr.c | 100 +++++++++++++++++++++++++++++++++++++
3 files changed, 112 insertions(+)
create mode 100644 drivers/soc/atmel/sfr.c
diff --git a/drivers/soc/atmel/Kconfig b/drivers/soc/atmel/Kconfig
index 05528139b023..50caf6db9c0e 100644
--- a/drivers/soc/atmel/Kconfig
+++ b/drivers/soc/atmel/Kconfig
@@ -5,3 +5,14 @@ config AT91_SOC_ID
default ARCH_AT91
help
Include support for the SoC bus on the Atmel ARM SoCs.
+
+config AT91_SOC_SFR
+ tristate "Special Function Registers support"
+ depends on ARCH_AT91 || COMPILE_TEST
+ help
+ This is a driver for the Special Function Registers available on
+ Atmel SAMA5Dx SoCs, providing access to specific aspects of the
+ integrated memory, bridge implementations, processor etc.
+
+ This driver can also be built as a module. If so, the module
+ will be called sfr.
diff --git a/drivers/soc/atmel/Makefile b/drivers/soc/atmel/Makefile
index 7ca355d10553..d849a897cd77 100644
--- a/drivers/soc/atmel/Makefile
+++ b/drivers/soc/atmel/Makefile
@@ -1,2 +1,3 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_AT91_SOC_ID) += soc.o
+obj-$(CONFIG_AT91_SOC_SFR) += sfr.o
diff --git a/drivers/soc/atmel/sfr.c b/drivers/soc/atmel/sfr.c
new file mode 100644
index 000000000000..1b4bc0bc0248
--- /dev/null
+++ b/drivers/soc/atmel/sfr.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sfr.c - driver for special function registers
+ *
+ * Copyright (C) 2019 Bootlin.
+ *
+ */
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/random.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define SFR_SN0 0x4c
+#define SFR_SN_SIZE 8
+
+struct atmel_sfr_priv {
+ struct regmap *regmap;
+};
+
+static int atmel_sfr_read(void *context, unsigned int offset,
+ void *buf, size_t bytes)
+{
+ struct atmel_sfr_priv *priv = context;
+ size_t len = bytes / 4;
+ int ret;
+
+ ret = regmap_bulk_read(priv->regmap, SFR_SN0 + offset,
+ buf, len);
+ if (ret == 0)
+ add_device_randomness(buf, len);
+
+ return ret;
+}
+
+static struct nvmem_config atmel_sfr_nvmem_config = {
+ .name = "atmel-sfr",
+ .read_only = true,
+ .word_size = 4,
+ .stride = 4,
+ .size = SFR_SN_SIZE,
+ .reg_read = atmel_sfr_read,
+};
+
+static int atmel_sfr_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct nvmem_device *nvmem;
+ struct atmel_sfr_priv *priv;
+
+ priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->regmap = syscon_node_to_regmap(np);
+ if (IS_ERR(priv->regmap)) {
+ dev_err(dev, "cannot get parent's regmap\n");
+ return PTR_ERR(priv->regmap);
+ }
+
+ atmel_sfr_nvmem_config.dev = dev;
+ atmel_sfr_nvmem_config.priv = priv;
+
+ nvmem = devm_nvmem_register(dev, &atmel_sfr_nvmem_config);
+ if (IS_ERR(nvmem)) {
+ dev_err(dev, "error registering nvmem config\n");
+ return PTR_ERR(nvmem);
+ }
+
+ return 0;
+}
+
+static const struct of_device_id atmel_sfr_dt_ids[] = {
+ {
+ .compatible = "atmel,sama5d2-sfr",
+ }, {
+ .compatible = "atmel,sama5d4-sfr",
+ }, {
+ /* sentinel */
+ },
+};
+MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
+
+static struct platform_driver atmel_sfr_driver = {
+ .probe = atmel_sfr_probe,
+ .driver = {
+ .name = "atmel-sfr",
+ .of_match_table = atmel_sfr_dt_ids,
+ },
+};
+module_platform_driver(atmel_sfr_driver);
+
+MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
+MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
+MODULE_LICENSE("GPL v2");
+
--
2.23.0
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v4] soc: at91: Add Atmel SFR SN (Serial Number) support
2019-10-04 12:24 [PATCH v4] soc: at91: Add Atmel SFR SN (Serial Number) support Kamel Bouhara
@ 2019-10-04 14:12 ` Tudor.Ambarus
0 siblings, 0 replies; 2+ messages in thread
From: Tudor.Ambarus @ 2019-10-04 14:12 UTC (permalink / raw)
To: kamel.bouhara, Nicolas.Ferre, alexandre.belloni,
Ludovic.Desroches, linux-arm-kernel
Cc: thomas.petazzoni
> +++ b/drivers/soc/atmel/sfr.c
cut
> +
> +static int atmel_sfr_read(void *context, unsigned int offset,
> + void *buf, size_t bytes)
> +{
> + struct atmel_sfr_priv *priv = context;
> + size_t len = bytes / 4;
> + int ret;
> +
> + ret = regmap_bulk_read(priv->regmap, SFR_SN0 + offset,
> + buf, len);
> + if (ret == 0)
> + add_device_randomness(buf, len);
this should be done at probe time, check drivers/nvmem/sunxi_sid.c for an example.
cut
> +MODULE_LICENSE("GPL v2");
> +
please don't forget about this line
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