nvme: use offset instead of a struct for registers

This makes life easier for future non-PCI drivers where access to the
registers might be more complicated.  Note that Linux drivers are
pretty evenly split between the two versions, and in fact the NVMe
driver already uses offsets for the doorbells.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
[Fixed CMBSZ offset]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/nvme/host/nvme.h

@@ -51,7 +51,7 @@ struct nvme_dev {
 	u32 db_stride;
 	u32 ctrl_config;
 	struct msix_entry *entry;
-	struct nvme_bar __iomem *bar;
+	void __iomem *bar;
 	struct list_head namespaces;
 	struct kref kref;
 	struct device *device;

drivers/nvme/host/pci.c

@@ -1322,7 +1322,7 @@ static void nvme_disable_queue(struct nvme_dev *dev, int qid)
 
 	/* Don't tell the adapter to delete the admin queue.
 	 * Don't tell a removed adapter to delete IO queues. */
-	if (qid && readl(&dev->bar->csts) != -1) {
+	if (qid && readl(dev->bar + NVME_REG_CSTS) != -1) {
 		adapter_delete_sq(dev, qid);
 		adapter_delete_cq(dev, qid);
 	}
@@ -1475,7 +1475,7 @@ static int nvme_wait_ready(struct nvme_dev *dev, u64 cap, bool enabled)
 
 	timeout = ((NVME_CAP_TIMEOUT(cap) + 1) * HZ / 2) + jiffies;
 
-	while ((readl(&dev->bar->csts) & NVME_CSTS_RDY) != bit) {
+	while ((readl(dev->bar + NVME_REG_CSTS) & NVME_CSTS_RDY) != bit) {
 		msleep(100);
 		if (fatal_signal_pending(current))
 			return -EINTR;
@@ -1500,7 +1500,7 @@ static int nvme_disable_ctrl(struct nvme_dev *dev, u64 cap)
 {
 	dev->ctrl_config &= ~NVME_CC_SHN_MASK;
 	dev->ctrl_config &= ~NVME_CC_ENABLE;
-	writel(dev->ctrl_config, &dev->bar->cc);
+	writel(dev->ctrl_config, dev->bar + NVME_REG_CC);
 
 	return nvme_wait_ready(dev, cap, false);
 }
@@ -1509,7 +1509,7 @@ static int nvme_enable_ctrl(struct nvme_dev *dev, u64 cap)
 {
 	dev->ctrl_config &= ~NVME_CC_SHN_MASK;
 	dev->ctrl_config |= NVME_CC_ENABLE;
-	writel(dev->ctrl_config, &dev->bar->cc);
+	writel(dev->ctrl_config, dev->bar + NVME_REG_CC);
 
 	return nvme_wait_ready(dev, cap, true);
 }
@@ -1521,10 +1521,10 @@ static int nvme_shutdown_ctrl(struct nvme_dev *dev)
 	dev->ctrl_config &= ~NVME_CC_SHN_MASK;
 	dev->ctrl_config |= NVME_CC_SHN_NORMAL;
 
-	writel(dev->ctrl_config, &dev->bar->cc);
+	writel(dev->ctrl_config, dev->bar + NVME_REG_CC);
 
 	timeout = SHUTDOWN_TIMEOUT + jiffies;
-	while ((readl(&dev->bar->csts) & NVME_CSTS_SHST_MASK) !=
+	while ((readl(dev->bar + NVME_REG_CSTS) & NVME_CSTS_SHST_MASK) !=
 							NVME_CSTS_SHST_CMPLT) {
 		msleep(100);
 		if (fatal_signal_pending(current))
@@ -1600,7 +1600,7 @@ static int nvme_configure_admin_queue(struct nvme_dev *dev)
 {
 	int result;
 	u32 aqa;
-	u64 cap = lo_hi_readq(&dev->bar->cap);
+	u64 cap = lo_hi_readq(dev->bar + NVME_REG_CAP);
 	struct nvme_queue *nvmeq;
 	/*
 	 * default to a 4K page size, with the intention to update this
@@ -1618,11 +1618,12 @@ static int nvme_configure_admin_queue(struct nvme_dev *dev)
 		return -ENODEV;
 	}
 
-	dev->subsystem = readl(&dev->bar->vs) >= NVME_VS(1, 1) ?
+	dev->subsystem = readl(dev->bar + NVME_REG_VS) >= NVME_VS(1, 1) ?
 						NVME_CAP_NSSRC(cap) : 0;
 
-	if (dev->subsystem && (readl(&dev->bar->csts) & NVME_CSTS_NSSRO))
-		writel(NVME_CSTS_NSSRO, &dev->bar->csts);
+	if (dev->subsystem &&
+	    (readl(dev->bar + NVME_REG_CSTS) & NVME_CSTS_NSSRO))
+		writel(NVME_CSTS_NSSRO, dev->bar + NVME_REG_CSTS);
 
 	result = nvme_disable_ctrl(dev, cap);
 	if (result < 0)
@@ -1645,9 +1646,9 @@ static int nvme_configure_admin_queue(struct nvme_dev *dev)
 	dev->ctrl_config |= NVME_CC_ARB_RR | NVME_CC_SHN_NONE;
 	dev->ctrl_config |= NVME_CC_IOSQES | NVME_CC_IOCQES;
 
-	writel(aqa, &dev->bar->aqa);
-	lo_hi_writeq(nvmeq->sq_dma_addr, &dev->bar->asq);
-	lo_hi_writeq(nvmeq->cq_dma_addr, &dev->bar->acq);
+	writel(aqa, dev->bar + NVME_REG_AQA);
+	lo_hi_writeq(nvmeq->sq_dma_addr, dev->bar + NVME_REG_ASQ);
+	lo_hi_writeq(nvmeq->cq_dma_addr, dev->bar + NVME_REG_ACQ);
 
 	result = nvme_enable_ctrl(dev, cap);
 	if (result)
@@ -1789,7 +1790,7 @@ static int nvme_subsys_reset(struct nvme_dev *dev)
 	if (!dev->subsystem)
 		return -ENOTTY;
 
-	writel(0x4E564D65, &dev->bar->nssr); /* "NVMe" */
+	writel(0x4E564D65, dev->bar + NVME_REG_NSSR); /* "NVMe" */
 	return 0;
 }
 
@@ -2076,14 +2077,14 @@ static int nvme_kthread(void *data)
 		spin_lock(&dev_list_lock);
 		list_for_each_entry_safe(dev, next, &dev_list, node) {
 			int i;
-			u32 csts = readl(&dev->bar->csts);
+			u32 csts = readl(dev->bar + NVME_REG_CSTS);
 
 			if ((dev->subsystem && (csts & NVME_CSTS_NSSRO)) ||
 							csts & NVME_CSTS_CFS) {
 				if (!__nvme_reset(dev)) {
 					dev_warn(dev->dev,
 						"Failed status: %x, reset controller\n",
-						readl(&dev->bar->csts));
+						readl(dev->bar + NVME_REG_CSTS));
 				}
 				continue;
 			}
@@ -2243,11 +2244,11 @@ static void __iomem *nvme_map_cmb(struct nvme_dev *dev)
 	if (!use_cmb_sqes)
 		return NULL;
 
-	dev->cmbsz = readl(&dev->bar->cmbsz);
+	dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
 	if (!(NVME_CMB_SZ(dev->cmbsz)))
 		return NULL;
 
-	cmbloc = readl(&dev->bar->cmbloc);
+	cmbloc = readl(dev->bar + NVME_REG_CMBLOC);
 
 	szu = (u64)1 << (12 + 4 * NVME_CMB_SZU(dev->cmbsz));
 	size = szu * NVME_CMB_SZ(dev->cmbsz);
@@ -2321,7 +2322,7 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
 				return -ENOMEM;
 			size = db_bar_size(dev, nr_io_queues);
 		} while (1);
-		dev->dbs = ((void __iomem *)dev->bar) + 4096;
+		dev->dbs = dev->bar + 4096;
 		adminq->q_db = dev->dbs;
 	}
 
@@ -2397,7 +2398,8 @@ static struct nvme_ns *nvme_find_ns(struct nvme_dev *dev, unsigned nsid)
 
 static inline bool nvme_io_incapable(struct nvme_dev *dev)
 {
-	return (!dev->bar || readl(&dev->bar->csts) & NVME_CSTS_CFS ||
+	return (!dev->bar ||
+		readl(dev->bar + NVME_REG_CSTS) & NVME_CSTS_CFS ||
 		dev->online_queues < 2);
 }
 
@@ -2478,7 +2480,7 @@ static int nvme_dev_add(struct nvme_dev *dev)
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	int res;
 	struct nvme_id_ctrl *ctrl;
-	int shift = NVME_CAP_MPSMIN(lo_hi_readq(&dev->bar->cap)) + 12;
+	int shift = NVME_CAP_MPSMIN(lo_hi_readq(dev->bar + NVME_REG_CAP)) + 12;
 
 	res = nvme_identify_ctrl(dev, &ctrl);
 	if (res) {
@@ -2554,7 +2556,7 @@ static int nvme_dev_map(struct nvme_dev *dev)
 	if (!dev->bar)
 		goto disable;
 
-	if (readl(&dev->bar->csts) == -1) {
+	if (readl(dev->bar + NVME_REG_CSTS) == -1) {
 		result = -ENODEV;
 		goto unmap;
 	}
@@ -2569,11 +2571,12 @@ static int nvme_dev_map(struct nvme_dev *dev)
 			goto unmap;
 	}
 
-	cap = lo_hi_readq(&dev->bar->cap);
+	cap = lo_hi_readq(dev->bar + NVME_REG_CAP);
+
 	dev->q_depth = min_t(int, NVME_CAP_MQES(cap) + 1, NVME_Q_DEPTH);
 	dev->db_stride = 1 << NVME_CAP_STRIDE(cap);
-	dev->dbs = ((void __iomem *)dev->bar) + 4096;
-	if (readl(&dev->bar->vs) >= NVME_VS(1, 2))
+	dev->dbs = dev->bar + 4096;
+	if (readl(dev->bar + NVME_REG_VS) >= NVME_VS(1, 2))
 		dev->cmb = nvme_map_cmb(dev);
 
 	return 0;
@@ -2632,7 +2635,8 @@ static void nvme_wait_dq(struct nvme_delq_ctx *dq, struct nvme_dev *dev)
 			 * queues than admin tags.
 			 */
 			set_current_state(TASK_RUNNING);
-			nvme_disable_ctrl(dev, lo_hi_readq(&dev->bar->cap));
+			nvme_disable_ctrl(dev,
+				lo_hi_readq(dev->bar + NVME_REG_CAP));
 			nvme_clear_queue(dev->queues[0]);
 			flush_kthread_worker(dq->worker);
 			nvme_disable_queue(dev, 0);
@@ -2808,7 +2812,7 @@ static void nvme_dev_shutdown(struct nvme_dev *dev)
 
 	if (dev->bar) {
 		nvme_freeze_queues(dev);
-		csts = readl(&dev->bar->csts);
+		csts = readl(dev->bar + NVME_REG_CSTS);
 	}
 	if (csts & NVME_CSTS_CFS || !(csts & NVME_CSTS_RDY)) {
 		for (i = dev->queue_count - 1; i >= 0; i--) {

drivers/nvme/host/scsi.c

@@ -611,7 +611,7 @@ static int nvme_trans_device_id_page(struct nvme_ns *ns, struct sg_io_hdr *hdr,
 
 	memset(inq_response, 0, alloc_len);
 	inq_response[1] = INQ_DEVICE_IDENTIFICATION_PAGE;    /* Page Code */
-	if (readl(&dev->bar->vs) >= NVME_VS(1, 1)) {
+	if (readl(dev->bar + NVME_REG_VS) >= NVME_VS(1, 1)) {
 		struct nvme_id_ns *id_ns;
 		void *eui;
 		int len;
@@ -623,7 +623,7 @@ static int nvme_trans_device_id_page(struct nvme_ns *ns, struct sg_io_hdr *hdr,
 
 		eui = id_ns->eui64;
 		len = sizeof(id_ns->eui64);
-		if (readl(&dev->bar->vs) >= NVME_VS(1, 2)) {
+		if (readl(dev->bar + NVME_REG_VS) >= NVME_VS(1, 2)) {
 			if (bitmap_empty(eui, len * 8)) {
 				eui = id_ns->nguid;
 				len = sizeof(id_ns->nguid);
@@ -2297,7 +2297,7 @@ static int nvme_trans_test_unit_ready(struct nvme_ns *ns,
 {
 	struct nvme_dev *dev = ns->dev;
 
-	if (!(readl(&dev->bar->csts) & NVME_CSTS_RDY))
+	if (!(readl(dev->bar + NVME_REG_CSTS) & NVME_CSTS_RDY))
 		return nvme_trans_completion(hdr, SAM_STAT_CHECK_CONDITION,
 					    NOT_READY, SCSI_ASC_LUN_NOT_READY,
 					    SCSI_ASCQ_CAUSE_NOT_REPORTABLE);

include/linux/nvme.h

@@ -17,20 +17,19 @@
 
 #include <linux/types.h>
 
-struct nvme_bar {
-	__u64			cap;	/* Controller Capabilities */
-	__u32			vs;	/* Version */
-	__u32			intms;	/* Interrupt Mask Set */
-	__u32			intmc;	/* Interrupt Mask Clear */
-	__u32			cc;	/* Controller Configuration */
-	__u32			rsvd1;	/* Reserved */
-	__u32			csts;	/* Controller Status */
-	__u32			nssr;	/* Subsystem Reset */
-	__u32			aqa;	/* Admin Queue Attributes */
-	__u64			asq;	/* Admin SQ Base Address */
-	__u64			acq;	/* Admin CQ Base Address */
-	__u32			cmbloc; /* Controller Memory Buffer Location */
-	__u32			cmbsz;  /* Controller Memory Buffer Size */
+enum {
+	NVME_REG_CAP	= 0x0000,	/* Controller Capabilities */
+	NVME_REG_VS	= 0x0008,	/* Version */
+	NVME_REG_INTMS	= 0x000c,	/* Interrupt Mask Set */
+	NVME_REG_INTMC	= 0x0010,	/* Interrupt Mask Set */
+	NVME_REG_CC	= 0x0014,	/* Controller Configuration */
+	NVME_REG_CSTS	= 0x001c,	/* Controller Status */
+	NVME_REG_NSSR	= 0x0020,	/* NVM Subsystem Reset */
+	NVME_REG_AQA	= 0x0024,	/* Admin Queue Attributes */
+	NVME_REG_ASQ	= 0x0028,	/* Admin SQ Base Address */
+	NVME_REG_ACQ	= 0x0030,	/* Admin SQ Base Address */
+	NVME_REG_CMBLOC = 0x0038,	/* Controller Memory Buffer Location */
+	NVME_REG_CMBSZ	= 0x003c,	/* Controller Memory Buffer Size */
 };
 
 #define NVME_CAP_MQES(cap)	((cap) & 0xffff)