Re: [PATCH] nvmem: add QTI SDAM driver

From: sthella
Date: Thu Dec 19 2019 - 05:29:32 EST

On 2019-12-18 11:44, Bjorn Andersson wrote:
On Tue 17 Dec 01:20 PST 2019, Shyam Kumar Thella wrote:

QTI SDAM driver allows PMIC peripherals to access the shared memory
that is available on QTI PMICs.

Change-Id: I40005646ab1fbba9e0e4aa68e0a61cfbc7b51ba6

No Change-Id upstream please.
OK. I will remove it in next patch set.

Signed-off-by: Shyam Kumar Thella <sthella@xxxxxxxxxxxxxx>
[..]
diff --git a/drivers/nvmem/qcom-spmi-sdam.c b/drivers/nvmem/qcom-spmi-sdam.c
new file mode 100644
index 0000000..e80a446
--- /dev/null
+++ b/drivers/nvmem/qcom-spmi-sdam.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2017 The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/nvmem-provider.h>
+#include <linux/regmap.h>
+
+#define SDAM_MEM_START 0x40
+#define REGISTER_MAP_ID 0x40
+#define REGISTER_MAP_VERSION 0x41
+#define SDAM_SIZE 0x44
+#define SDAM_PBS_TRIG_SET 0xE5
+#define SDAM_PBS_TRIG_CLR 0xE6
+
+struct sdam_chip {
+ struct platform_device *pdev;

As written right now, pdev is unused. But if you stash struct device *
here instead you can replace your pr_err() with dev_err() using this,
for better error messages.

I will use dev_err messages in next patchset.
+ struct regmap *regmap;
+ int base;

This would look better as a unsigned int.
OK. I will do it in next patch set.

+ int size;

Ditto, or perhaps even size_t.
OK. I will do it.

+};
+
+/* read only register offsets */
+static const u8 sdam_ro_map[] = {
+ REGISTER_MAP_ID,
+ REGISTER_MAP_VERSION,
+ SDAM_SIZE
+};
+
+static bool is_valid(struct sdam_chip *sdam, unsigned int offset, size_t len)

Please do prefix this with "sdam_"
OK. I will prefix is_valid and is_ro with "sdam_".

+{
+ int sdam_mem_end = SDAM_MEM_START + sdam->size - 1;
+
+ if (!len)
+ return false;
+
+ if (offset >= SDAM_MEM_START && offset <= sdam_mem_end
+ && (offset + len - 1) <= sdam_mem_end)
+ return true;
+ else if ((offset == SDAM_PBS_TRIG_SET || offset == SDAM_PBS_TRIG_CLR)
+ && (len == 1))
+ return true;
+
+ return false;
+}
+
+static bool is_ro(unsigned int offset, size_t len)

Ditto
OK.

+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(sdam_ro_map); i++)
+ if (offset <= sdam_ro_map[i] && (offset + len) > sdam_ro_map[i])
+ return true;
+
+ return false;
+}
+
+static int sdam_read(void *priv, unsigned int offset, void *val, size_t bytes)
+{
+ struct sdam_chip *sdam = priv;
+ int rc;
+
+ if (!is_valid(sdam, offset, bytes)) {
+ pr_err("Invalid SDAM offset 0x%02x len=%zd\n", offset, bytes);

Use %#x instead of 0x%02x
OK. Will do it in next patch set.

+ return -EINVAL;
+ }
+
+ rc = regmap_bulk_read(sdam->regmap, sdam->base + offset, val, bytes);
+ if (rc < 0)
+ pr_err("Failed to read SDAM offset 0x%02x len=%zd, rc=%d\n",
+ offset, bytes, rc);
+
+ return rc;
+}
+
+static int sdam_write(void *priv, unsigned int offset, void *val, size_t bytes)
+{
+ struct sdam_chip *sdam = priv;
+ int rc;
+
+ if (!is_valid(sdam, offset, bytes)) {
+ pr_err("Invalid SDAM offset 0x%02x len=%zd\n", offset, bytes);
+ return -EINVAL;
+ }
+
+ if (is_ro(offset, bytes)) {
+ pr_err("Invalid write offset 0x%02x len=%zd\n", offset, bytes);
+ return -EINVAL;
+ }
+
+ rc = regmap_bulk_write(sdam->regmap, sdam->base + offset, val, bytes);
+ if (rc < 0)
+ pr_err("Failed to write SDAM offset 0x%02x len=%zd, rc=%d\n",
+ offset, bytes, rc);
+
+ return rc;
+}
+
+static int sdam_probe(struct platform_device *pdev)
+{
+ struct sdam_chip *sdam;
+ struct nvmem_device *nvmem;
+ struct nvmem_config *sdam_config;
+ unsigned int val = 0;

No need to initialize this.
OK. I will remove initialization in next patch set.

+ int rc;
+
+ sdam = devm_kzalloc(&pdev->dev, sizeof(*sdam), GFP_KERNEL);
+ if (!sdam)
+ return -ENOMEM;
+
+ sdam_config = devm_kzalloc(&pdev->dev, sizeof(*sdam_config),
+ GFP_KERNEL);

Can't this be included in struct sdam_chip, for a single allocation?
OK. I will make this a member in struct sdam_chip and eliminate need for dynamic allocation.

+ if (!sdam_config)
+ return -ENOMEM;
+
+ sdam->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+ if (!sdam->regmap) {
+ pr_err("Failed to get regmap handle\n");

dev_err(&pdev->dev, ...);
OK. I will change all pr_err()... to dev_err().

+ return -ENXIO;
+ }
+
+ rc = of_property_read_u32(pdev->dev.of_node, "reg", &sdam->base);

In other words, base must be u32.
OK. This will be changed to u32 in next patchs et.

+ if (rc < 0) {
+ pr_err("Failed to get SDAM base, rc=%d\n", rc);
+ return -EINVAL;
+ }
+
+ rc = regmap_read(sdam->regmap, sdam->base + SDAM_SIZE, &val);
+ if (rc < 0) {
+ pr_err("Failed to read SDAM_SIZE rc=%d\n", rc);
+ return -EINVAL;
+ }
+ sdam->size = val * 32;
+
+ sdam_config->dev = &pdev->dev;
+ sdam_config->name = "spmi_sdam";
+ sdam_config->id = pdev->id;
+ sdam_config->owner = THIS_MODULE,
+ sdam_config->stride = 1;
+ sdam_config->word_size = 1;
+ sdam_config->reg_read = sdam_read;
+ sdam_config->reg_write = sdam_write;
+ sdam_config->priv = sdam;
+
+ nvmem = nvmem_register(sdam_config);
+ if (IS_ERR(nvmem)) {
+ pr_err("Failed to register SDAM nvmem device rc=%ld\n",
+ PTR_ERR(nvmem));
+ return -ENXIO;
+ }
+ platform_set_drvdata(pdev, nvmem);
+
+ pr_info("SDAM base=0x%04x size=%d registered successfully\n",
+ sdam->base, sdam->size);

Please don't print notifications in the kernel log. You can possibly use
dev_dbg(). Or just look for devices in
/sys/bus/platform/drivers/qcom,spmi-sdam/
OK. I would usedev_dbg() to serve the purpose.

+
+ return 0;
+}
+
+static int sdam_remove(struct platform_device *pdev)

Instead of using nvmem_register(), use devm_nvmem_register() and just
omit the remote function completely - which also allows you to drop the
platform_set_drvdata() above.
Yes. You are right. That will help omit remove and platform_set_drvdata().

+{
+ struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+ return nvmem_unregister(nvmem);
+}
+
+static const struct of_device_id sdam_match_table[] = {
+ {.compatible = "qcom,spmi-sdam"},

Please add a space after { and before }.
OK. I will add spaces.

+ {},
+};
+
+static struct platform_driver sdam_driver = {
+ .driver = {
+ .name = "qcom,spmi-sdam",
+ .of_match_table = sdam_match_table,
+ },
+ .probe = sdam_probe,
+ .remove = sdam_remove,
+};
+
+static int __init sdam_init(void)
+{
+ return platform_driver_register(&sdam_driver);
+}
+subsys_initcall(sdam_init);

module_platform_driver(sdam_driver), unless you have some strong
arguments for why this needs to be subsys_initcall
There are some critical sybsystems which depend on nvmem data. So I would prefer using subsys_initcall().

Regards,
Bjorn

+
+static void __exit sdam_exit(void)
+{
+ return platform_driver_unregister(&sdam_driver);
+}
+module_exit(sdam_exit);
+
+MODULE_DESCRIPTION("QCOM SPMI SDAM driver");
+MODULE_LICENSE("GPL v2");
--
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