diff options
Diffstat (limited to 'drivers/misc/mei/dma-ring.c')
| -rw-r--r-- | drivers/misc/mei/dma-ring.c | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/drivers/misc/mei/dma-ring.c b/drivers/misc/mei/dma-ring.c new file mode 100644 index 0000000000..ef56f849b2 --- /dev/null +++ b/drivers/misc/mei/dma-ring.c @@ -0,0 +1,269 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright(c) 2016-2018 Intel Corporation. All rights reserved. + */ +#include <linux/dma-mapping.h> +#include <linux/mei.h> + +#include "mei_dev.h" + +/** + * mei_dmam_dscr_alloc() - allocate a managed coherent buffer + * for the dma descriptor + * @dev: mei_device + * @dscr: dma descriptor + * + * Return: + * * 0 - on success or zero allocation request + * * -EINVAL - if size is not power of 2 + * * -ENOMEM - of allocation has failed + */ +static int mei_dmam_dscr_alloc(struct mei_device *dev, + struct mei_dma_dscr *dscr) +{ + if (!dscr->size) + return 0; + + if (WARN_ON(!is_power_of_2(dscr->size))) + return -EINVAL; + + if (dscr->vaddr) + return 0; + + dscr->vaddr = dmam_alloc_coherent(dev->dev, dscr->size, &dscr->daddr, + GFP_KERNEL); + if (!dscr->vaddr) + return -ENOMEM; + + return 0; +} + +/** + * mei_dmam_dscr_free() - free a managed coherent buffer + * from the dma descriptor + * @dev: mei_device + * @dscr: dma descriptor + */ +static void mei_dmam_dscr_free(struct mei_device *dev, + struct mei_dma_dscr *dscr) +{ + if (!dscr->vaddr) + return; + + dmam_free_coherent(dev->dev, dscr->size, dscr->vaddr, dscr->daddr); + dscr->vaddr = NULL; +} + +/** + * mei_dmam_ring_free() - free dma ring buffers + * @dev: mei device + */ +void mei_dmam_ring_free(struct mei_device *dev) +{ + int i; + + for (i = 0; i < DMA_DSCR_NUM; i++) + mei_dmam_dscr_free(dev, &dev->dr_dscr[i]); +} + +/** + * mei_dmam_ring_alloc() - allocate dma ring buffers + * @dev: mei device + * + * Return: -ENOMEM on allocation failure 0 otherwise + */ +int mei_dmam_ring_alloc(struct mei_device *dev) +{ + int i; + + for (i = 0; i < DMA_DSCR_NUM; i++) + if (mei_dmam_dscr_alloc(dev, &dev->dr_dscr[i])) + goto err; + + return 0; + +err: + mei_dmam_ring_free(dev); + return -ENOMEM; +} + +/** + * mei_dma_ring_is_allocated() - check if dma ring is allocated + * @dev: mei device + * + * Return: true if dma ring is allocated + */ +bool mei_dma_ring_is_allocated(struct mei_device *dev) +{ + return !!dev->dr_dscr[DMA_DSCR_HOST].vaddr; +} + +static inline +struct hbm_dma_ring_ctrl *mei_dma_ring_ctrl(struct mei_device *dev) +{ + return (struct hbm_dma_ring_ctrl *)dev->dr_dscr[DMA_DSCR_CTRL].vaddr; +} + +/** + * mei_dma_ring_reset() - reset the dma control block + * @dev: mei device + */ +void mei_dma_ring_reset(struct mei_device *dev) +{ + struct hbm_dma_ring_ctrl *ctrl = mei_dma_ring_ctrl(dev); + + if (!ctrl) + return; + + memset(ctrl, 0, sizeof(*ctrl)); +} + +/** + * mei_dma_copy_from() - copy from dma ring into buffer + * @dev: mei device + * @buf: data buffer + * @offset: offset in slots. + * @n: number of slots to copy. + */ +static size_t mei_dma_copy_from(struct mei_device *dev, unsigned char *buf, + u32 offset, u32 n) +{ + unsigned char *dbuf = dev->dr_dscr[DMA_DSCR_DEVICE].vaddr; + + size_t b_offset = offset << 2; + size_t b_n = n << 2; + + memcpy(buf, dbuf + b_offset, b_n); + + return b_n; +} + +/** + * mei_dma_copy_to() - copy to a buffer to the dma ring + * @dev: mei device + * @buf: data buffer + * @offset: offset in slots. + * @n: number of slots to copy. + */ +static size_t mei_dma_copy_to(struct mei_device *dev, unsigned char *buf, + u32 offset, u32 n) +{ + unsigned char *hbuf = dev->dr_dscr[DMA_DSCR_HOST].vaddr; + + size_t b_offset = offset << 2; + size_t b_n = n << 2; + + memcpy(hbuf + b_offset, buf, b_n); + + return b_n; +} + +/** + * mei_dma_ring_read() - read data from the ring + * @dev: mei device + * @buf: buffer to read into: may be NULL in case of droping the data. + * @len: length to read. + */ +void mei_dma_ring_read(struct mei_device *dev, unsigned char *buf, u32 len) +{ + struct hbm_dma_ring_ctrl *ctrl = mei_dma_ring_ctrl(dev); + u32 dbuf_depth; + u32 rd_idx, rem, slots; + + if (WARN_ON(!ctrl)) + return; + + dev_dbg(dev->dev, "reading from dma %u bytes\n", len); + + if (!len) + return; + + dbuf_depth = dev->dr_dscr[DMA_DSCR_DEVICE].size >> 2; + rd_idx = READ_ONCE(ctrl->dbuf_rd_idx) & (dbuf_depth - 1); + slots = mei_data2slots(len); + + /* if buf is NULL we drop the packet by advancing the pointer.*/ + if (!buf) + goto out; + + if (rd_idx + slots > dbuf_depth) { + buf += mei_dma_copy_from(dev, buf, rd_idx, dbuf_depth - rd_idx); + rem = slots - (dbuf_depth - rd_idx); + rd_idx = 0; + } else { + rem = slots; + } + + mei_dma_copy_from(dev, buf, rd_idx, rem); +out: + WRITE_ONCE(ctrl->dbuf_rd_idx, ctrl->dbuf_rd_idx + slots); +} + +static inline u32 mei_dma_ring_hbuf_depth(struct mei_device *dev) +{ + return dev->dr_dscr[DMA_DSCR_HOST].size >> 2; +} + +/** + * mei_dma_ring_empty_slots() - calaculate number of empty slots in dma ring + * @dev: mei_device + * + * Return: number of empty slots + */ +u32 mei_dma_ring_empty_slots(struct mei_device *dev) +{ + struct hbm_dma_ring_ctrl *ctrl = mei_dma_ring_ctrl(dev); + u32 wr_idx, rd_idx, hbuf_depth, empty; + + if (!mei_dma_ring_is_allocated(dev)) + return 0; + + if (WARN_ON(!ctrl)) + return 0; + + /* easier to work in slots */ + hbuf_depth = mei_dma_ring_hbuf_depth(dev); + rd_idx = READ_ONCE(ctrl->hbuf_rd_idx); + wr_idx = READ_ONCE(ctrl->hbuf_wr_idx); + + if (rd_idx > wr_idx) + empty = rd_idx - wr_idx; + else + empty = hbuf_depth - (wr_idx - rd_idx); + + return empty; +} + +/** + * mei_dma_ring_write - write data to dma ring host buffer + * + * @dev: mei_device + * @buf: data will be written + * @len: data length + */ +void mei_dma_ring_write(struct mei_device *dev, unsigned char *buf, u32 len) +{ + struct hbm_dma_ring_ctrl *ctrl = mei_dma_ring_ctrl(dev); + u32 hbuf_depth; + u32 wr_idx, rem, slots; + + if (WARN_ON(!ctrl)) + return; + + dev_dbg(dev->dev, "writing to dma %u bytes\n", len); + hbuf_depth = mei_dma_ring_hbuf_depth(dev); + wr_idx = READ_ONCE(ctrl->hbuf_wr_idx) & (hbuf_depth - 1); + slots = mei_data2slots(len); + + if (wr_idx + slots > hbuf_depth) { + buf += mei_dma_copy_to(dev, buf, wr_idx, hbuf_depth - wr_idx); + rem = slots - (hbuf_depth - wr_idx); + wr_idx = 0; + } else { + rem = slots; + } + + mei_dma_copy_to(dev, buf, wr_idx, rem); + + WRITE_ONCE(ctrl->hbuf_wr_idx, ctrl->hbuf_wr_idx + slots); +} |