drivers: reset: STi SoC system configuration reset controller support

This patch adds a reset controller implementation for STMicroelectronics
STi family SoCs; it allows a group of related reset like controls found
in multiple system configuration registers to be represented by a single
controller device. System configuration registers are accessed through
the regmap framework and the mfd/syscon driver.

The implementation optionally supports waiting for the reset action to
be acknowledged in a separate status register and supports both
active high and active low reset lines. These properties are common across
all the reset channels in a specific reset controller instance, hence
all channels in a paritcular controller are expected to behave in the
same way.

Signed-off-by: Stephen Gallimore <stephen.gallimore@st.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>

1 files changed, 69 insertions, 0 deletions

diff --git a/drivers/reset/sti/reset-syscfg.h b/drivers/reset/sti/reset-syscfg.h
new file mode 100644
index 000000000000..2cc2283bac40
--- /dev/null
+++ b/drivers/reset/sti/reset-syscfg.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2013 STMicroelectronics (R&D) Limited
+ * Author: Stephen Gallimore <stephen.gallimore@st.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#ifndef __STI_RESET_SYSCFG_H
+#define __STI_RESET_SYSCFG_H
+
+#include <linux/device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+/**
+ * Reset channel description for a system configuration register based
+ * reset controller.
+ *
+ * @compatible: Compatible string of the syscon regmap containing this
+ *              channel's control and ack (status) bits.
+ * @reset: Regmap field description of the channel's reset bit.
+ * @ack: Regmap field description of the channel's acknowledge bit.
+ */
+struct syscfg_reset_channel_data {
+        const char *compatible;
+        struct reg_field reset;
+        struct reg_field ack;
+};
+
+#define _SYSCFG_RST_CH(_c, _rr, _rb, _ar, _ab)          \
+        { .compatible   = _c,                           \
+          .reset        = REG_FIELD(_rr, _rb, _rb),     \
+          .ack          = REG_FIELD(_ar, _ab, _ab), }
+
+#define _SYSCFG_RST_CH_NO_ACK(_c, _rr, _rb)             \
+        { .compatible   = _c,                   \
+          .reset        = REG_FIELD(_rr, _rb, _rb), }
+
+/**
+ * Description of a system configuration register based reset controller.
+ *
+ * @wait_for_ack: The controller will wait for reset assert and de-assert to
+ *                be "ack'd" in a channel's ack field.
+ * @active_low: Are the resets in this controller active low, i.e. clearing
+ *              the reset bit puts the hardware into reset.
+ * @nr_channels: The number of reset channels in this controller.
+ * @channels: An array of reset channel descriptions.
+ */
+struct syscfg_reset_controller_data {
+        bool wait_for_ack;
+        bool active_low;
+        int nr_channels;
+        const struct syscfg_reset_channel_data *channels;
+};
+
+/**
+ * syscfg_reset_probe(): platform device probe function used by syscfg
+ *                       reset controller drivers. This registers a reset
+ *                       controller configured by the OF match data for
+ *                       the compatible device which should be of type
+ *                       "struct syscfg_reset_controller_data".
+ *
+ * @pdev: platform device
+ */
+int syscfg_reset_probe(struct platform_device *pdev);
+
+#endif /* __STI_RESET_SYSCFG_H */