mirror of
https://github.com/Ysurac/openmptcprouter.git
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93 lines
2.6 KiB
Diff
93 lines
2.6 KiB
Diff
From edd25a77e69b7c546c28077e5dffe72c54c0afe8 Mon Sep 17 00:00:00 2001
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From: Linus Walleij <linus.walleij@linaro.org>
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Date: Thu, 21 Sep 2023 22:18:12 +0200
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Subject: [PATCH 2/4] rtc: rtc7301: Support byte-addressed IO
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The old RTC7301 driver in OpenWrt used byte access, but the
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current mainline Linux driver uses 32bit word access.
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Make this configurable using device properties using the
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standard property "reg-io-width" in e.g. device tree.
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This is needed for the USRobotics USR8200 which has the
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chip connected using byte accesses.
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Debugging and testing by Howard Harte.
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Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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---
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drivers/rtc/rtc-r7301.c | 35 +++++++++++++++++++++++++++++++++--
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1 file changed, 33 insertions(+), 2 deletions(-)
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--- a/drivers/rtc/rtc-r7301.c
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+++ b/drivers/rtc/rtc-r7301.c
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@@ -14,6 +14,7 @@
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/delay.h>
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+#include <linux/property.h>
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#include <linux/regmap.h>
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#include <linux/platform_device.h>
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#include <linux/rtc.h>
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@@ -55,12 +56,23 @@ struct rtc7301_priv {
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u8 bank;
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};
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-static const struct regmap_config rtc7301_regmap_config = {
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+/*
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+ * When the device is memory-mapped, some platforms pack the registers into
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+ * 32-bit access using the lower 8 bits at each 4-byte stride, while others
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+ * expose them as simply consecutive bytes.
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+ */
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+static const struct regmap_config rtc7301_regmap_32_config = {
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.reg_bits = 32,
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.val_bits = 8,
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.reg_stride = 4,
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};
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+static const struct regmap_config rtc7301_regmap_8_config = {
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+ .reg_bits = 8,
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+ .val_bits = 8,
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+ .reg_stride = 1,
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+};
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+
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static u8 rtc7301_read(struct rtc7301_priv *priv, unsigned int reg)
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{
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int reg_stride = regmap_get_reg_stride(priv->regmap);
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@@ -356,7 +368,9 @@ static int __init rtc7301_rtc_probe(stru
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void __iomem *regs;
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struct rtc7301_priv *priv;
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struct rtc_device *rtc;
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+ static const struct regmap_config *mapconf;
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int ret;
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+ u32 val;
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priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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@@ -366,8 +380,25 @@ static int __init rtc7301_rtc_probe(stru
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if (IS_ERR(regs))
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return PTR_ERR(regs);
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+ ret = device_property_read_u32(&dev->dev, "reg-io-width", &val);
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+ if (ret)
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+ /* Default to 32bit accesses */
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+ val = 4;
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+
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+ switch (val) {
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+ case 1:
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+ mapconf = &rtc7301_regmap_8_config;
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+ break;
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+ case 4:
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+ mapconf = &rtc7301_regmap_32_config;
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+ break;
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+ default:
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+ dev_err(&dev->dev, "invalid reg-io-width %d\n", val);
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+ return -EINVAL;
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+ }
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+
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priv->regmap = devm_regmap_init_mmio(&dev->dev, regs,
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- &rtc7301_regmap_config);
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+ mapconf);
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if (IS_ERR(priv->regmap))
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return PTR_ERR(priv->regmap);
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