ixp4xx_eth: make ptp support a platform driver

After the recent ixp4xx cleanups, the ptp driver has gained a
build failure in some configurations:

drivers/net/ethernet/xscale/ptp_ixp46x.c: In function 'ptp_ixp_init':
drivers/net/ethernet/xscale/ptp_ixp46x.c:290:51: error: 'IXP4XX_TIMESYNC_BASE_VIRT' undeclared (first use in this function)

Avoid the last bit of hardcoded constants from platform headers
by turning the ptp driver bit into a platform driver and passing
the IRQ and MMIO address as resources.

This is a bit tricky:

- The interface between the two drivers is now the new
ixp46x_ptp_find() function, replacing the global
ixp46x_phc_index variable. The call is done as late
as possible, in hwtstamp_set(), to ensure that the
ptp device is fully probed.

- As the ptp driver is now called by the network driver, the
link dependency is reversed, which in turn requires a small
Makefile hack

- The GPIO number is still left hardcoded. This is clearly not
great, but it can be addressed later. Note that commit 98ac0cc270b7
("ARM: ixp4xx: Convert to MULTI_IRQ_HANDLER") changed the
IRQ number to something meaningless. Passing the correct IRQ
in a resource fixes this.

- When the PTP driver is disabled, ethtool .get_ts_info()
now correctly lists only software timestamping regardless
of the hardware.

Signed-off-by: Arnd Bergmann <[e-mail]>
[Fix a missing include]
Signed-off-by: Linus Walleij <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

arch/arm/mach-ixp4xx/common.c

···
 	.resource	= ixp46x_i2c_resources
 };
 
+static struct resource ixp46x_ptp_resources[] = {
+	DEFINE_RES_MEM(IXP4XX_TIMESYNC_BASE_PHYS, SZ_4K),
+	DEFINE_RES_IRQ_NAMED(IRQ_IXP4XX_GPIO8, "master"),
+	DEFINE_RES_IRQ_NAMED(IRQ_IXP4XX_GPIO7, "slave"),
+};
+
+static struct platform_device ixp46x_ptp = {
+	.name		= "ptp-ixp46x",
+	.id		= -1,
+	.resource	= ixp46x_ptp_resources,
+	.num_resources	= ARRAY_SIZE(ixp46x_ptp_resources),
+};
+
 static struct platform_device *ixp46x_devices[] __initdata = {
 	&ixp46x_hwrandom_device,
 	&ixp46x_i2c_controller,
+	&ixp46x_ptp,
 };
 
 unsigned long ixp4xx_exp_bus_size;

drivers/net/ethernet/xscale/Kconfig

···
 	  on IXP4xx processor.
 
 config PTP_1588_CLOCK_IXP46X
-	tristate "Intel IXP46x as PTP clock"
+	bool "Intel IXP46x as PTP clock"
 	depends on IXP4XX_ETH
-	depends on PTP_1588_CLOCK
+	depends on PTP_1588_CLOCK=y || PTP_1588_CLOCK=IXP4XX_ETH
 	default y
 	help
 	  This driver adds support for using the IXP46X as a PTP

drivers/net/ethernet/xscale/Makefile

···
 # Makefile for the Intel XScale IXP device drivers.
 #
 
+# Keep this link order to avoid deferred probing
+ifdef CONFIG_PTP_1588_CLOCK_IXP46X
+obj-$(CONFIG_IXP4XX_ETH)		+= ptp_ixp46x.o
+endif
+
 obj-$(CONFIG_IXP4XX_ETH)		+= ixp4xx_eth.o
-obj-$(CONFIG_PTP_1588_CLOCK_IXP46X)	+= ptp_ixp46x.o

drivers/net/ethernet/xscale/ixp46x_ts.h

···
 #define TX_SNAPSHOT_LOCKED (1<<0)
 #define RX_SNAPSHOT_LOCKED (1<<1)
 
-/* The ptp_ixp46x module will set this variable */
-extern int ixp46x_phc_index;
+#if IS_ENABLED(CONFIG_PTP_1588_CLOCK_IXP46X)
+int ixp46x_ptp_find(struct ixp46x_ts_regs *__iomem *regs, int *phc_index);
+#else
+static inline int ixp46x_ptp_find(struct ixp46x_ts_regs *__iomem *regs, int *phc_index)
+{
+	*regs = NULL;
+	*phc_index = -1;
+
+	return -ENODEV;
+}
+#endif
 
 #endif

drivers/net/ethernet/xscale/ixp4xx_eth.c

···
 
 struct port {
 	struct eth_regs __iomem *regs;
+	struct ixp46x_ts_regs __iomem *timesync_regs;
+	int phc_index;
 	struct npe *npe;
 	struct net_device *netdev;
 	struct napi_struct napi;
···
 
 	ch = PORT2CHANNEL(port);
 
-	regs = (struct ixp46x_ts_regs __iomem *) IXP4XX_TIMESYNC_BASE_VIRT;
+	regs = port->timesync_regs;
 
 	val = __raw_readl(&regs->channel[ch].ch_event);
 
···
 
 	ch = PORT2CHANNEL(port);
 
-	regs = (struct ixp46x_ts_regs __iomem *) IXP4XX_TIMESYNC_BASE_VIRT;
+	regs = port->timesync_regs;
 
 	/*
 	 * This really stinks, but we have to poll for the Tx time stamp.
···
 	struct hwtstamp_config cfg;
 	struct ixp46x_ts_regs *regs;
 	struct port *port = netdev_priv(netdev);
+	int ret;
 	int ch;
 
 	if (copy_from_user(&cfg, ifr->ifr_data, sizeof(cfg)))
···
 	if (cfg.flags) /* reserved for future extensions */
 		return -EINVAL;
 
+	ret = ixp46x_ptp_find(&port->timesync_regs, &port->phc_index);
+	if (ret)
+		return ret;
+
 	ch = PORT2CHANNEL(port);
-	regs = (struct ixp46x_ts_regs __iomem *) IXP4XX_TIMESYNC_BASE_VIRT;
+	regs = port->timesync_regs;
 
 	if (cfg.tx_type != HWTSTAMP_TX_OFF && cfg.tx_type != HWTSTAMP_TX_ON)
 		return -ERANGE;
···
 	strlcpy(info->bus_info, "internal", sizeof(info->bus_info));
 }
 
-int ixp46x_phc_index = -1;
-EXPORT_SYMBOL_GPL(ixp46x_phc_index);
-
 static int ixp4xx_get_ts_info(struct net_device *dev,
 			      struct ethtool_ts_info *info)
 {
-	if (!cpu_is_ixp46x()) {
+	struct port *port = netdev_priv(dev);
+
+	if (port->phc_index < 0)
+		ixp46x_ptp_find(&port->timesync_regs, &port->phc_index);
+
+	info->phc_index = port->phc_index;
+
+	if (info->phc_index < 0) {
 		info->so_timestamping =
 			SOF_TIMESTAMPING_TX_SOFTWARE |
 			SOF_TIMESTAMPING_RX_SOFTWARE |
 			SOF_TIMESTAMPING_SOFTWARE;
-		info->phc_index = -1;
 		return 0;
 	}
 	info->so_timestamping =
 		SOF_TIMESTAMPING_TX_HARDWARE |
 		SOF_TIMESTAMPING_RX_HARDWARE |
 		SOF_TIMESTAMPING_RAW_HARDWARE;
-	info->phc_index = ixp46x_phc_index;
 	info->tx_types =
 		(1 << HWTSTAMP_TX_OFF) |
 		(1 << HWTSTAMP_TX_ON);
···
 	port = netdev_priv(ndev);
 	port->netdev = ndev;
 	port->id = plat->npe;
+	port->phc_index = -1;
 
 	/* Get the port resource and remap */
 	port->regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);

drivers/net/ethernet/xscale/ptp_ixp46x.c

···
  * Copyright (C) 2010 OMICRON electronics GmbH
  */
 #include <linux/device.h>
+#include <linux/module.h>
 #include <linux/err.h>
 #include <linux/gpio.h>
 #include <linux/init.h>
···
 #include <linux/irq.h>
 #include <linux/kernel.h>
 #include <linux/ptp_clock_kernel.h>
+#include <linux/platform_device.h>
 #include <linux/soc/ixp4xx/cpu.h>
 #include <linux/module.h>
 #include <mach/ixp4xx-regs.h>
···
 #define DRIVER		"ptp_ixp46x"
 #define N_EXT_TS	2
 #define MASTER_GPIO	8
-#define MASTER_IRQ	25
 #define SLAVE_GPIO	7
-#define SLAVE_IRQ	24
 
 struct ixp_clock {
 	struct ixp46x_ts_regs *regs;
···
 	struct ptp_clock_info caps;
 	int exts0_enabled;
 	int exts1_enabled;
+	int slave_irq;
+	int master_irq;
 };
 
-DEFINE_SPINLOCK(register_lock);
+static DEFINE_SPINLOCK(register_lock);
 
 /*
  * Register access functions
···
 	return irq;
 }
 
-static void __exit ptp_ixp_exit(void)
+int ixp46x_ptp_find(struct ixp46x_ts_regs *__iomem *regs, int *phc_index)
 {
-	free_irq(MASTER_IRQ, &ixp_clock);
-	free_irq(SLAVE_IRQ, &ixp_clock);
-	ixp46x_phc_index = -1;
+	*regs = ixp_clock.regs;
+	*phc_index = ptp_clock_index(ixp_clock.ptp_clock);
+
+	if (!ixp_clock.ptp_clock)
+		return -EPROBE_DEFER;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ixp46x_ptp_find);
+
+static int ptp_ixp_remove(struct platform_device *pdev)
+{
+	free_irq(ixp_clock.master_irq, &ixp_clock);
+	free_irq(ixp_clock.slave_irq, &ixp_clock);
 	ptp_clock_unregister(ixp_clock.ptp_clock);
+	ixp_clock.ptp_clock = NULL;
+
+	return 0;
 }
 
-static int __init ptp_ixp_init(void)
+static int ptp_ixp_probe(struct platform_device *pdev)
 {
-	if (!cpu_is_ixp46x())
-		return -ENODEV;
-
-	ixp_clock.regs =
-		(struct ixp46x_ts_regs __iomem *) IXP4XX_TIMESYNC_BASE_VIRT;
+	ixp_clock.regs = devm_platform_ioremap_resource(pdev, 0);
+	ixp_clock.master_irq = platform_get_irq(pdev, 0);
+	ixp_clock.slave_irq = platform_get_irq(pdev, 1);
+	if (IS_ERR(ixp_clock.regs) ||
+	    !ixp_clock.master_irq || !ixp_clock.slave_irq)
+		return -ENXIO;
 
 	ixp_clock.caps = ptp_ixp_caps;
 
···
 	if (IS_ERR(ixp_clock.ptp_clock))
 		return PTR_ERR(ixp_clock.ptp_clock);
 
-	ixp46x_phc_index = ptp_clock_index(ixp_clock.ptp_clock);
-
 	__raw_writel(DEFAULT_ADDEND, &ixp_clock.regs->addend);
 	__raw_writel(1, &ixp_clock.regs->trgt_lo);
 	__raw_writel(0, &ixp_clock.regs->trgt_hi);
 	__raw_writel(TTIPEND, &ixp_clock.regs->event);
 
-	if (MASTER_IRQ != setup_interrupt(MASTER_GPIO)) {
+	if (ixp_clock.master_irq != setup_interrupt(MASTER_GPIO)) {
 		pr_err("failed to setup gpio %d as irq\n", MASTER_GPIO);
 		goto no_master;
 	}
-	if (SLAVE_IRQ != setup_interrupt(SLAVE_GPIO)) {
+	if (ixp_clock.slave_irq != setup_interrupt(SLAVE_GPIO)) {
 		pr_err("failed to setup gpio %d as irq\n", SLAVE_GPIO);
 		goto no_slave;
 	}
 
 	return 0;
 no_slave:
-	free_irq(MASTER_IRQ, &ixp_clock);
+	free_irq(ixp_clock.master_irq, &ixp_clock);
 no_master:
 	ptp_clock_unregister(ixp_clock.ptp_clock);
+	ixp_clock.ptp_clock = NULL;
 	return -ENODEV;
 }
 
-module_init(ptp_ixp_init);
-module_exit(ptp_ixp_exit);
+static struct platform_driver ptp_ixp_driver = {
+	.driver.name = "ptp-ixp46x",
+	.driver.suppress_bind_attrs = true,
+	.probe = ptp_ixp_probe,
+	.remove = ptp_ixp_remove,
+};
+module_platform_driver(ptp_ixp_driver);
 
 MODULE_AUTHOR("Richard Cochran <[e-mail]>");
 MODULE_DESCRIPTION("PTP clock using the IXP46X timer");