bcm53xx: add support for reading NVRAM based on DT mapping
This is required for devices that use NVRAM data for detecting currently used firmware partition (e.g. Linksys devices). Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
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Rafał Miłecki
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From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
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Date: Tue, 2 Mar 2021 08:23:35 +0100
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Subject: [PATCH] dt-bindings: firmware: add Broadcom's NVRAM memory mapping
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NVRAM structure contains device data and can be accessed using MMIO.
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Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
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---
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.../bindings/firmware/brcm,nvram.yaml | 41 +++++++++++++++++++
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1 file changed, 41 insertions(+)
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create mode 100644 Documentation/devicetree/bindings/firmware/brcm,nvram.yaml
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--- /dev/null
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+++ b/Documentation/devicetree/bindings/firmware/brcm,nvram.yaml
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@@ -0,0 +1,41 @@
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+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
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+%YAML 1.2
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+---
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+$id: "http://devicetree.org/schemas/firmware/brcm,nvram.yaml#"
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+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
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+
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+title: Broadcom's NVRAM
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+
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+maintainers:
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+ - Rafał Miłecki <rafal@milecki.pl>
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+
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+description: |
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+ NVRAM is a structure containing device specific environment variables.
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+ It is used for storing device configuration, booting parameters and
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+ calibration data.
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+
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+ It's required very early in booting process and so is made available
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+ using memory mapping.
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+
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+ NVRAM can be found on Broadcom BCM47xx MIPS, Northstar ARM Cortex-A9
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+ and some more devices.
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+
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+properties:
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+ compatible:
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+ const: brcm,nvram
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+
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+ reg:
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+ description: memory region with NVRAM data
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+ maxItems: 1
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+
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+required:
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+ - reg
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+
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+additionalProperties: false
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+
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+examples:
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+ - |
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+ nvram@1e000000 {
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+ compatible = "brcm,nvram";
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+ reg = <0x1e000000 0x10000>;
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+ };
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@ -0,0 +1,85 @@
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From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
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Date: Tue, 2 Mar 2021 08:33:13 +0100
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Subject: [PATCH] firmware: bcm47xx_nvram: support platform device "brcm,nvram"
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Add support for platform device providing mapping resource. This allows
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reading NVRAM based on DT mapping binding. It's required for devices
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that boot depending on NVRAM stored setup and provides early access to
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NVRAM data.
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Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
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---
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drivers/firmware/broadcom/bcm47xx_nvram.c | 55 +++++++++++++++++++++++
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1 file changed, 55 insertions(+)
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--- a/drivers/firmware/broadcom/bcm47xx_nvram.c
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+++ b/drivers/firmware/broadcom/bcm47xx_nvram.c
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@@ -13,6 +13,7 @@
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/mtd/mtd.h>
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+#include <linux/platform_device.h>
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#include <linux/bcm47xx_nvram.h>
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#define NVRAM_MAGIC 0x48534C46 /* 'FLSH' */
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@@ -162,6 +163,60 @@ static int nvram_init(void)
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return -ENXIO;
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}
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+static int brcm_nvram_probe(struct platform_device *pdev)
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+{
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+ struct nvram_header __iomem *header;
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+ struct device *dev = &pdev->dev;
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+ struct resource *res;
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+ void __iomem *mmio;
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+ size_t copy_len;
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+
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+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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+ if (!res) {
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+ dev_err(dev, "Failed to get resource\n");
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+ return -ENODEV;
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+ }
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+
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+ mmio = ioremap(res->start, resource_size(res));
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+ if (!mmio)
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+ return -ENOMEM;
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+
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+ header = (struct nvram_header *)mmio;
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+ copy_len = DIV_ROUND_UP(sizeof(*header) + header->len, 4);
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+ if (header->magic != NVRAM_MAGIC) {
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+ dev_err(dev, "No NVRAM found at %pR\n", res);
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+ return -EPROTO;
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+ } else if (copy_len > resource_size(res)) {
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+ dev_err(dev, "NVRAM size exceeds %pR\n", res);
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+ return -ERANGE;
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+ } else if (copy_len >= NVRAM_SPACE) {
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+ dev_err(dev, "NVRAM size exceeds buffer size %d\n", NVRAM_SPACE);
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+ return -ENOMEM;
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+ }
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+
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+ __ioread32_copy(nvram_buf, mmio, copy_len);
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+ nvram_buf[NVRAM_SPACE - 1] = '\0';
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+
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+ iounmap(mmio);
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+
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+ return 0;
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+}
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+
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+static const struct of_device_id brcm_nvram_of_match[] = {
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+ { .compatible = "brcm,nvram "},
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+ {},
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+};
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+
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+static struct platform_driver brcm_nvram_driver = {
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+ .driver = {
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+ .name = "brcm_nvram",
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+ .of_match_table = brcm_nvram_of_match,
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+ },
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+ .probe = brcm_nvram_probe,
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+};
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+
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+module_platform_driver(brcm_nvram_driver);
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+
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int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
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{
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char *var, *value, *end, *eq;
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