[PATCH v3] mtd: hyperbus: add Renesas RPC-IF driver

[Sergei Shtylyov <sergei.shtylyov@gmail.com>]

From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

Add the HyperFLash driver for the Renesas RPC-IF.  It's the "front end"
driver using the "back end" APIs in the main driver to talk to the real
hardware.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

---
This patch is against the 'mtd/next' branch of the MTD 'linux.git' repo.

Changes in version 3:
- factored out rpcif_hb_prepare_read() out of the read16() and copy_from()
  driver methods and rpcif_hb_prepare_write() out of the write16() method;
- added #define's fo the HyperBus command bits to the HyperBus header file,
  made use of them in the driver;
- removed #ifndef CONFIG_MTD_CFI_BE_BYTE_SWAP fromn the driver; convertged the
  'select' line to 'depends on' line inm the Kconfig option;
- added CONFIG_COMPILE_TEST to the 'depends on' line of the driver's Kconfig
  option;
- changed HyperFlash to HyperBus in the driver's Kconfig option's help text;
- killed a stray space before the declaration of the 'struct rpcif_hyperbus'.

Changes in version 2:
- added 'select MTD_CFI_ADV_OPTIONS' to the Kconfig entry, added #ifndef
  CONFIG_MTD_CFI_BE_BYTE_SWAP #error in the driver, and removed  be16_to_cpu()
  call in the read16() method;
- zeroed the target and burst type bits of the HyperBus command codes;
- passed the address of 16-bit entity to rpcif_prepare() in the copy_from()
  method;
- added an empty line between rpcif_prepare() and rpcif_drirmap_read() calls
  in the copy_from() method;
- renamed rpcif_io_xfer() to rpcif_manual_xfer();
- removed the C++ style comments to rpcif_prepare() calls;
- removed dev_err() call from the probe() method;
- renamed the 'status' local variable to 'error' in the probe() method;
- extended the driver copyright to this year.

 drivers/mtd/hyperbus/Kconfig  |    7 +
 drivers/mtd/hyperbus/Makefile |    1 
 drivers/mtd/hyperbus/rpc-if.c |  170 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/mtd/hyperbus.h  |   11 ++
 4 files changed, 189 insertions(+)

Index: linux/drivers/mtd/hyperbus/Kconfig
===================================================================
--- linux.orig/drivers/mtd/hyperbus/Kconfig
+++ linux/drivers/mtd/hyperbus/Kconfig
@@ -22,4 +22,11 @@ config HBMC_AM654
 	 This is the driver for HyperBus controller on TI's AM65x and
 	 other SoCs
 
+config RPCIF_HYPERBUS
+	tristate "Renesas RPC-IF HyperBus driver"
+	depends on RENESAS_RPCIF || COMPILE_TEST
+	depends on MTD_CFI_BE_BYTE_SWAP
+	help
+	  This option includes Renesas RPC-IF HyperBus support.
+
 endif # MTD_HYPERBUS
Index: linux/drivers/mtd/hyperbus/Makefile
===================================================================
--- linux.orig/drivers/mtd/hyperbus/Makefile
+++ linux/drivers/mtd/hyperbus/Makefile
@@ -2,3 +2,4 @@
 
 obj-$(CONFIG_MTD_HYPERBUS)	+= hyperbus-core.o
 obj-$(CONFIG_HBMC_AM654)	+= hbmc-am654.o
+obj-$(CONFIG_RPCIF_HYPERBUS)	+= rpc-if.o
Index: linux/drivers/mtd/hyperbus/rpc-if.c
===================================================================
--- /dev/null
+++ linux/drivers/mtd/hyperbus/rpc-if.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Linux driver for RPC-IF HyperFlash
+ *
+ * Copyright (C) 2019-2020 Cogent Embedded, Inc.
+ */
+
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mtd/hyperbus.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mux/consumer.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#include <memory/renesas-rpc-if.h>
+
+struct	rpcif_hyperbus {
+	struct rpcif rpc;
+	struct hyperbus_ctlr ctlr;
+	struct hyperbus_device hbdev;
+};
+
+static const struct rpcif_op rpcif_op_tmpl = {
+	.cmd = {
+		.buswidth = 8,
+		.ddr = true,
+	},
+	.ocmd = {
+		.buswidth = 8,
+		.ddr = true,
+	},
+	.addr = {
+		.nbytes = 1,
+		.buswidth = 8,
+		.ddr = true,
+	},
+	.data = {
+		.buswidth = 8,
+		.ddr = true,
+	},
+};
+
+static void rpcif_hb_prepare_read(struct rpcif *rpc, void *to,
+				  unsigned long from, ssize_t len)
+{
+	struct rpcif_op op = rpcif_op_tmpl;
+
+	op.cmd.opcode = HYPERBUS_RW_READ | HYPERBUS_AS_MEM;
+	op.addr.val = from >> 1;
+	op.dummy.buswidth = 1;
+	op.dummy.ncycles = 15;
+	op.data.dir = RPCIF_DATA_IN;
+	op.data.nbytes = len;
+	op.data.buf.in = to;
+
+	rpcif_prepare(rpc, &op, NULL, NULL);
+}
+
+static void rpcif_hb_prepare_write(struct rpcif *rpc, unsigned long to,
+				   void *from, ssize_t len)
+{
+	struct rpcif_op op = rpcif_op_tmpl;
+
+	op.cmd.opcode = HYPERBUS_RW_WRITE | HYPERBUS_AS_MEM;
+	op.addr.val = to >> 1;
+	op.data.dir = RPCIF_DATA_OUT;
+	op.data.nbytes = len;
+	op.data.buf.out = from;
+
+	rpcif_prepare(rpc, &op, NULL, NULL);
+}
+
+static u16 rpcif_hb_read16(struct hyperbus_device *hbdev, unsigned long addr)
+{
+	struct rpcif_hyperbus *hyperbus =
+		container_of(hbdev, struct rpcif_hyperbus, hbdev);
+	map_word data;
+
+	rpcif_hb_prepare_read(&hyperbus->rpc, &data, addr, 2);
+
+	rpcif_manual_xfer(&hyperbus->rpc);
+
+	return data.x[0];
+}
+
+static void rpcif_hb_write16(struct hyperbus_device *hbdev, unsigned long addr,
+			     u16 data)
+{
+	struct rpcif_hyperbus *hyperbus =
+		container_of(hbdev, struct rpcif_hyperbus, hbdev);
+
+	rpcif_hb_prepare_write(&hyperbus->rpc, addr, &data, 2);
+
+	rpcif_manual_xfer(&hyperbus->rpc);
+}
+
+static void rpcif_hb_copy_from(struct hyperbus_device *hbdev, void *to,
+			       unsigned long from, ssize_t len)
+{
+	struct rpcif_hyperbus *hyperbus =
+		container_of(hbdev, struct rpcif_hyperbus, hbdev);
+
+	rpcif_hb_prepare_read(&hyperbus->rpc, to, from, len);
+
+	rpcif_dirmap_read(&hyperbus->rpc, from, len, to);
+}
+
+static const struct hyperbus_ops rpcif_hb_ops = {
+	.read16 = rpcif_hb_read16,
+	.write16 = rpcif_hb_write16,
+	.copy_from = rpcif_hb_copy_from,
+};
+
+static int rpcif_hb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rpcif_hyperbus *hyperbus;
+	int error;
+
+	hyperbus = devm_kzalloc(dev, sizeof(*hyperbus), GFP_KERNEL);
+	if (!hyperbus)
+		return -ENOMEM;
+
+	rpcif_sw_init(&hyperbus->rpc, pdev->dev.parent);
+
+	platform_set_drvdata(pdev, hyperbus);
+
+	rpcif_enable_rpm(&hyperbus->rpc);
+
+	rpcif_hw_init(&hyperbus->rpc, true);
+
+	hyperbus->hbdev.map.size = hyperbus->rpc.size;
+	hyperbus->hbdev.map.virt = hyperbus->rpc.dirmap;
+
+	hyperbus->ctlr.dev = dev;
+	hyperbus->ctlr.ops = &rpcif_hb_ops;
+	hyperbus->hbdev.ctlr = &hyperbus->ctlr;
+	hyperbus->hbdev.np = of_get_next_child(pdev->dev.parent->of_node, NULL);
+	error = hyperbus_register_device(&hyperbus->hbdev);
+	if (error)
+		rpcif_disable_rpm(&hyperbus->rpc);
+
+	return error;
+}
+
+static int rpcif_hb_remove(struct platform_device *pdev)
+{
+	struct rpcif_hyperbus *hyperbus = platform_get_drvdata(pdev);
+	int error = hyperbus_unregister_device(&hyperbus->hbdev);
+	struct rpcif *rpc = dev_get_drvdata(pdev->dev.parent);
+
+	rpcif_disable_rpm(rpc);
+	return error;
+}
+
+static struct platform_driver rpcif_platform_driver = {
+	.probe	= rpcif_hb_probe,
+	.remove	= rpcif_hb_remove,
+	.driver	= {
+		.name	= "rpc-if-hyperflash",
+	},
+};
+
+module_platform_driver(rpcif_platform_driver);
+
+MODULE_DESCRIPTION("Renesas RPC-IF HyperFlash driver");
+MODULE_LICENSE("GPL v2");
Index: linux/include/linux/mtd/hyperbus.h
===================================================================
--- linux.orig/include/linux/mtd/hyperbus.h
+++ linux/include/linux/mtd/hyperbus.h
@@ -8,6 +8,17 @@
 
 #include <linux/mtd/map.h>
 
+/* HyperBus command bits */
+#define HYPERBUS_RW	0x80	/* R/W# */
+#define HYPERBUS_RW_WRITE 0
+#define HYPERBUS_RW_READ 0x80
+#define HYPERBUS_AS	0x40	/* Address Space */
+#define HYPERBUS_AS_MEM	0
+#define HYPERBUS_AS_REG	0x40
+#define HYPERBUS_BT	0x20	/* Burst Type */
+#define HYPERBUS_BT_WRAPPED 0
+#define HYPERBUS_BT_LINEAR 0x20
+
 enum hyperbus_memtype {
 	HYPERFLASH,
 	HYPERRAM,

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