[PATCH v6 2/2] mfd: Add Samsung Exynos Low Power Audio Subsystem driver

[Sylwester Nawrocki <s.nawrocki@samsung.com>]

This patch adds common driver for the Top block of the Samsung Exynos
SoC Low Power Audio Subsystem.  This is a minimal driver which prepares
resources for IP blocks like I2S, audio DMA and UART and exposes
a regmap for the Top block registers.  Also system power ops are added
to ensure the Audio Subsystem is operational after system suspend/resume
cycle.

Signed-off-by: Inha Song <ideal.song@samsung.com>
Signed-off-by: Beomho Seo <beomho.seo@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
---

Changes since v5:
 - BIT() used for the register bit macro definitions,
 - removed unneeded dev->of_node test,
 - exynos_lpass_{suspend,resume} functions compiled-in conditionally,
 - added comments for struct exynos_lpass fields.

Changes since v4:
 - none.

Changes since v3:
 - moved from sound/soc/samsung and rewritten as a MFD driver,
 - PMU register definitions moved to include/linux/mfd/syscon/exynos5-pmu.h,
 - added regmap for LPASS Top SFR region,
 - cleaned up register bit field defintions.

Changes since v2:
 - move misplaced SND_SAMSUNG_AUDSS Kconfig symbol addition
   to this patch.
---
 drivers/mfd/Kconfig                    |   8 ++
 drivers/mfd/Makefile                   |   1 +
 drivers/mfd/exynos-lpass.c             | 187 +++++++++++++++++++++++++++++++++
 include/linux/mfd/syscon/exynos5-pmu.h |   4 +-
 4 files changed, 199 insertions(+), 1 deletion(-)
 create mode 100644 drivers/mfd/exynos-lpass.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 2d1fb64..a7ec890 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -281,6 +281,14 @@ config MFD_DLN2
 	  etc. must be enabled in order to use the functionality of
 	  the device.
 
+config MFD_EXYNOS_LPASS
+	tristate "Samsung Exynos SoC Low Power Audio Subsystem"
+	select MFD_CORE
+	select REGMAP_MMIO
+	help
+	  Select this option to enable support for Samsung Exynos Low Power
+	  Audio Subsystem.
+
 config MFD_MC13XXX
 	tristate
 	depends on (SPI_MASTER || I2C)
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 2ba3ba3..41510bb 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
 obj-$(CONFIG_MFD_CROS_EC)	+= cros_ec.o
 obj-$(CONFIG_MFD_CROS_EC_I2C)	+= cros_ec_i2c.o
 obj-$(CONFIG_MFD_CROS_EC_SPI)	+= cros_ec_spi.o
+obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
 
 rtsx_pci-objs			:= rtsx_pcr.o rts5209.o rts5229.o rtl8411.o rts5227.o rts5249.o
 obj-$(CONFIG_MFD_RTSX_PCI)	+= rtsx_pci.o
diff --git a/drivers/mfd/exynos-lpass.c b/drivers/mfd/exynos-lpass.c
new file mode 100644
index 0000000..578ac7b
--- /dev/null
+++ b/drivers/mfd/exynos-lpass.c
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2015 - 2016 Samsung Electronics Co., Ltd.
+ *
+ * Authors: Inha Song <ideal.song@samsung.com>
+ *          Sylwester Nawrocki <s.nawrocki@samsung.com>
+ *
+ * Samsung Exynos SoC series Low Power Audio Subsystem driver.
+ *
+ * This module provides regmap for the Top SFR region and instantiates
+ * devices for IP blocks like DMAC, I2S, UART.
+ *
+ * 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.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mfd/syscon.h>
+#include <linux/mfd/syscon/exynos5-pmu.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+/* LPASS Top register definitions */
+#define SFR_LPASS_CORE_SW_RESET		0x08
+#define  LPASS_SB_SW_RESET		BIT(11)
+#define  LPASS_UART_SW_RESET		BIT(10)
+#define  LPASS_PCM_SW_RESET		BIT(9)
+#define  LPASS_I2S_SW_RESET		BIT(8)
+#define  LPASS_WDT1_SW_RESET		BIT(4)
+#define  LPASS_WDT0_SW_RESET		BIT(3)
+#define  LPASS_TIMER_SW_RESET		BIT(2)
+#define  LPASS_MEM_SW_RESET		BIT(1)
+#define  LPASS_DMA_SW_RESET		BIT(0)
+
+#define SFR_LPASS_INTR_CA5_MASK		0x48
+#define SFR_LPASS_INTR_CPU_MASK		0x58
+#define  LPASS_INTR_APM			BIT(9)
+#define  LPASS_INTR_MIF			BIT(8)
+#define  LPASS_INTR_TIMER		BIT(7)
+#define  LPASS_INTR_DMA			BIT(6)
+#define  LPASS_INTR_GPIO		BIT(5)
+#define  LPASS_INTR_I2S			BIT(4)
+#define  LPASS_INTR_PCM			BIT(3)
+#define  LPASS_INTR_SLIMBUS		BIT(2)
+#define  LPASS_INTR_UART		BIT(1)
+#define  LPASS_INTR_SFR			BIT(0)
+
+struct exynos_lpass {
+	/* pointer to the Power Management Unit regmap */
+	struct regmap *pmu;
+	/* pointer to the LPASS TOP regmap */
+	struct regmap *top;
+};
+
+static void exynos_lpass_core_sw_reset(struct exynos_lpass *lpass, int mask)
+{
+	unsigned int val = 0;
+
+	regmap_read(lpass->top, SFR_LPASS_CORE_SW_RESET, &val);
+
+	val &= ~mask;
+	regmap_write(lpass->top, SFR_LPASS_CORE_SW_RESET, val);
+
+	usleep_range(100, 150);
+
+	val |= mask;
+	regmap_write(lpass->top, SFR_LPASS_CORE_SW_RESET, val);
+}
+
+static void exynos_lpass_enable(struct exynos_lpass *lpass)
+{
+	/* Unmask SFR, DMA and I2S interrupt */
+	regmap_write(lpass->top, SFR_LPASS_INTR_CA5_MASK,
+		     LPASS_INTR_SFR | LPASS_INTR_DMA | LPASS_INTR_I2S);
+
+	regmap_write(lpass->top, SFR_LPASS_INTR_CPU_MASK,
+		     LPASS_INTR_SFR | LPASS_INTR_DMA | LPASS_INTR_I2S);
+
+	/* Activate related PADs from retention state */
+	regmap_write(lpass->pmu, EXYNOS5433_PAD_RETENTION_AUD_OPTION,
+		     EXYNOS5433_PAD_INITIATE_WAKEUP_FROM_LOWPWR);
+
+	exynos_lpass_core_sw_reset(lpass, LPASS_I2S_SW_RESET);
+	exynos_lpass_core_sw_reset(lpass, LPASS_DMA_SW_RESET);
+	exynos_lpass_core_sw_reset(lpass, LPASS_MEM_SW_RESET);
+}
+
+static void exynos_lpass_disable(struct exynos_lpass *lpass)
+{
+	/* Mask any unmasked IP interrupt sources */
+	regmap_write(lpass->top, SFR_LPASS_INTR_CPU_MASK, 0);
+	regmap_write(lpass->top, SFR_LPASS_INTR_CA5_MASK, 0);
+
+	/* Deactivate related PADs from retention state */
+	regmap_write(lpass->pmu, EXYNOS5433_PAD_RETENTION_AUD_OPTION, 0);
+}
+
+static const struct regmap_config exynos_lpass_reg_conf = {
+	.reg_bits	= 32,
+	.reg_stride	= 4,
+	.val_bits	= 32,
+	.max_register	= 0xfc,
+	.fast_io	= true,
+};
+
+static int exynos_lpass_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct exynos_lpass *lpass;
+	void __iomem *base_top;
+	struct resource *res;
+
+	lpass = devm_kzalloc(dev, sizeof(*lpass), GFP_KERNEL);
+	if (!lpass)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base_top = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base_top))
+		return PTR_ERR(base_top);
+
+	lpass->top = regmap_init_mmio(dev, base_top,
+					&exynos_lpass_reg_conf);
+	if (IS_ERR(lpass->top)) {
+		dev_err(dev, "LPASS top regmap initialization failed\n");
+		return PTR_ERR(lpass->top);
+	}
+
+	lpass->pmu = syscon_regmap_lookup_by_phandle(dev->of_node,
+						"samsung,pmu-syscon");
+	if (IS_ERR(lpass->pmu)) {
+		dev_err(dev, "Failed to lookup PMU regmap\n");
+		return PTR_ERR(lpass->pmu);
+	}
+
+	platform_set_drvdata(pdev, lpass);
+	exynos_lpass_enable(lpass);
+
+	return of_platform_populate(dev->of_node, NULL, NULL, dev);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int exynos_lpass_suspend(struct device *dev)
+{
+	struct exynos_lpass *lpass = dev_get_drvdata(dev);
+
+	exynos_lpass_disable(lpass);
+
+	return 0;
+}
+
+static int exynos_lpass_resume(struct device *dev)
+{
+	struct exynos_lpass *lpass = dev_get_drvdata(dev);
+
+	exynos_lpass_enable(lpass);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(lpass_pm_ops, exynos_lpass_suspend,
+					exynos_lpass_resume);
+
+static const struct of_device_id exynos_lpass_of_match[] = {
+	{ .compatible = "samsung,exynos5433-lpass" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, exynos_lpass_of_match);
+
+static struct platform_driver exynos_lpass_driver = {
+	.driver = {
+		.name		= "exynos-lpass",
+		.pm		= &lpass_pm_ops,
+		.of_match_table	= exynos_lpass_of_match,
+	},
+	.probe	= exynos_lpass_probe,
+};
+module_platform_driver(exynos_lpass_driver);
+
+MODULE_DESCRIPTION("Samsung Low Power Audio Subsystem driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/mfd/syscon/exynos5-pmu.h b/include/linux/mfd/syscon/exynos5-pmu.h
index 76f30f9..c28ff21 100644
--- a/include/linux/mfd/syscon/exynos5-pmu.h
+++ b/include/linux/mfd/syscon/exynos5-pmu.h
@@ -43,8 +43,10 @@
 #define EXYNOS5433_MIPI_PHY2_CONTROL		(0x718)
 
 #define EXYNOS5_PHY_ENABLE			BIT(0)
-
 #define EXYNOS5_MIPI_PHY_S_RESETN		BIT(1)
 #define EXYNOS5_MIPI_PHY_M_RESETN		BIT(2)
 
+#define EXYNOS5433_PAD_RETENTION_AUD_OPTION		(0x3028)
+#define EXYNOS5433_PAD_INITIATE_WAKEUP_FROM_LOWPWR	BIT(28)
+
 #endif /* _LINUX_MFD_SYSCON_PMU_EXYNOS5_H_ */
-- 
1.9.1