Re: [PATCH v2 2/3] ARM: qcom: Add coincell charger driver

On 07/15/2015 12:08 PM, Tim Bird wrote:

On 07/14/2015 06:11 PM, Stephen Boyd wrote:

quoted

On 07/14/2015 04:26 PM, Tim Bird wrote:

quoted

   3 files changed, 166 insertions(+)
   create mode 100644 drivers/misc/qcom-coincell.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 42c3852..0909869 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig

@@ -271,6 +271,17 @@ config HP_ILO
   	  To compile this driver as a module, choose M here: the
   	  module will be called hpilo.
   
+config QCOM_COINCELL
+	tristate "Qualcomm coincell charger support"
+	depends on OF

It looks like it would compile fine without OF, so can we drop this
dependency? Or make it into

   depends on MFD_SPMI_PMIC || COMPILE_TEST

?

I think I had CONFIG_OF off one time, and I spent the better
part of the afternoon trying to figure out why the driver wasn't
loading.  So it compiles but doesn't actually work.
But I think a dependency on MFD_SPMI_PMIC solves this issue.
So, OK on the second suggestion.

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quoted

+	select REGMAP

This config wouldn't be necessary either then because it would be 
selected implicitly by the SPMI parent driver.

quoted

quoted

diff --git a/drivers/misc/qcom-coincell.c b/drivers/misc/qcom-coincell.c
new file mode 100644
index 0000000..9c019e4
--- /dev/null
+++ b/drivers/misc/qcom-coincell.c

@@ -0,0 +1,154 @@
+/* Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2015, Sony Mobile Communications Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+struct qcom_coincell {
+	struct device	*dev;
+	struct regmap	*regmap;
+	u32		base_addr;
+};
+
+#define QCOM_COINCELL_REG_RSET		0x44
+#define QCOM_COINCELL_REG_VSET		0x45
+#define QCOM_COINCELL_REG_ENABLE	0x46
+
+#define QCOM_COINCELL_ENABLE		BIT(7)
+
+static const int qcom_rset_map[] = {2100, 1700, 1200, 800};
+static const int qcom_vset_map[] = {2500, 3200, 3100, 3000};

Nitpick: put spaces around those braces.

OK.  I presume you mean like this:
{ 2100, 1700, 1200, 800 };

Yep.

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quoted

+	return rc;
+}
+
+static int qcom_coincell_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct qcom_coincell *chgr;
+	u32 rset, vset, enable;
+	int rc;
+
+	if (!node) {
+		dev_err(&pdev->dev, "%s: device node missing\n", __func__);
+		return -ENODEV;
+	}

Does this happen?

Probably not any more.  The only way this device gets initialized now
is via OF operations.  This code was forward-ported from when this driver
also operated as a platform device.  In the current situation, I don't
know of a way for the kernel to get here if of_node is missing
(but I'm not an OF expert, and I didn't want to start using
a NULL of_node.)

What does of_property_read...() do with a NULL node?

I'm pretty sure it returns success or nothing when the node is NULL.

I'm a little leery of taking this check out, but if you think it's
OK I'm fine doing it.

I'll fix any problems with the removal of the check :)

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+
+	chgr = devm_kzalloc(&pdev->dev, sizeof(*chgr), GFP_KERNEL);
+	if (!chgr)
+		return -ENOMEM;
+
+	chgr->dev = &pdev->dev;
+
+	chgr->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!chgr->regmap) {
+		dev_err(chgr->dev, "Unable to get regmap\n");
+		return -EINVAL;
+	}
+
+	rc = of_property_read_u32(node, "reg", &chgr->base_addr);
+	if (rc)
+		return rc;
+
+	rc = of_property_read_u32(node, "qcom,rset-ohms", &rset);
+	if (rc) {
+		dev_err(chgr->dev, "can't find 'qcom,rset-ohms' in DT block");
+		return rc;
+	}
+
+	rc = of_property_read_u32(node, "qcom,vset-millivolts", &vset);
+	if (rc) {
+		dev_err(chgr->dev,
+			"can't find 'qcom,vset-millivolts' in DT block");
+		return rc;
+	}
+
+	rc = of_property_read_u32(node, "qcom,charge-enable", &enable);

This should be a bool:

      enable = of_property_read_bool(node, "qcom,charge-enable");

OK.
  

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+	if (rc)
+		enable = 0;
+
+	rc = qcom_coincell_chgr_config(chgr, rset, vset, enable);
+
+	return rc;

This could be simplified to a return qcom_coincell_chrg_config() too.

Also, do we even need the chgr structure allocated anywhere besides on 
the stack? It seems that it will be memory that's just lying around for 
no use after probe.

-- 
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