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Subject[RFC PATCH v2 1/3] USB: use genalloc for USB HCs with local memory
Date
From: Laurentiu Tudor <laurentiu.tudor@nxp.com>

For HCs that have local memory, replace the current DMA API usage
with a genalloc generic allocator to manage the mappings for these
devices.
This is in preparation for dropping the existing "coherent" dma
mem declaration APIs. Current implementation was relying on a short
circuit in the DMA API that in the end, was acting as an allocator
for these type of devices.

For context, see thread here: https://lkml.org/lkml/2019/4/22/357

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
---
drivers/usb/core/buffer.c | 12 +++++++++++-
drivers/usb/host/ohci-hcd.c | 23 ++++++++++++++++++-----
include/linux/usb/hcd.h | 3 +++
3 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/core/buffer.c b/drivers/usb/core/buffer.c
index f641342cdec0..5729801e82e0 100644
--- a/drivers/usb/core/buffer.c
+++ b/drivers/usb/core/buffer.c
@@ -16,6 +16,7 @@
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
+#include <linux/genalloc.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>

@@ -136,6 +137,10 @@ void *hcd_buffer_alloc(
if (size <= pool_max[i])
return dma_pool_alloc(hcd->pool[i], mem_flags, dma);
}
+
+ if (hcd->driver->flags & HCD_LOCAL_MEM)
+ return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);
+
return dma_alloc_coherent(hcd->self.sysdev, size, dma, mem_flags);
}

@@ -165,5 +170,10 @@ void hcd_buffer_free(
return;
}
}
- dma_free_coherent(hcd->self.sysdev, size, addr, dma);
+
+ if (hcd->driver->flags & HCD_LOCAL_MEM)
+ gen_pool_free(hcd->localmem_pool, (unsigned long)addr,
+ size);
+ else
+ dma_free_coherent(hcd->self.sysdev, size, addr, dma);
}
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index 210181fd98d2..f9462c372943 100644
--- a/drivers/usb/host/ohci-hcd.c
+++ b/drivers/usb/host/ohci-hcd.c
@@ -40,6 +40,7 @@
#include <linux/dmapool.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
+#include <linux/genalloc.h>

#include <asm/io.h>
#include <asm/irq.h>
@@ -505,8 +506,15 @@ static int ohci_init (struct ohci_hcd *ohci)
timer_setup(&ohci->io_watchdog, io_watchdog_func, 0);
ohci->prev_frame_no = IO_WATCHDOG_OFF;

- ohci->hcca = dma_alloc_coherent (hcd->self.controller,
- sizeof(*ohci->hcca), &ohci->hcca_dma, GFP_KERNEL);
+ if (hcd->driver->flags & HCD_LOCAL_MEM)
+ ohci->hcca = gen_pool_dma_alloc(hcd->localmem_pool,
+ sizeof(*ohci->hcca),
+ &ohci->hcca_dma);
+ else
+ ohci->hcca = dma_alloc_coherent(hcd->self.controller,
+ sizeof(*ohci->hcca),
+ &ohci->hcca_dma,
+ GFP_KERNEL);
if (!ohci->hcca)
return -ENOMEM;

@@ -990,9 +998,14 @@ static void ohci_stop (struct usb_hcd *hcd)
remove_debug_files (ohci);
ohci_mem_cleanup (ohci);
if (ohci->hcca) {
- dma_free_coherent (hcd->self.controller,
- sizeof *ohci->hcca,
- ohci->hcca, ohci->hcca_dma);
+ if (hcd->driver->flags & HCD_LOCAL_MEM)
+ gen_pool_free(hcd->localmem_pool,
+ (unsigned long)ohci->hcca,
+ sizeof(*ohci->hcca));
+ else
+ dma_free_coherent(hcd->self.controller,
+ sizeof(*ohci->hcca),
+ ohci->hcca, ohci->hcca_dma);
ohci->hcca = NULL;
ohci->hcca_dma = 0;
}
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index 695931b03684..0fee81ef5d52 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -215,6 +215,9 @@ struct usb_hcd {
#define HC_IS_RUNNING(state) ((state) & __ACTIVE)
#define HC_IS_SUSPENDED(state) ((state) & __SUSPEND)

+ /* allocator for HCs having local memory */
+ struct gen_pool *localmem_pool;
+
/* more shared queuing code would be good; it should support
* smarter scheduling, handle transaction translators, etc;
* input size of periodic table to an interrupt scheduler.
--
2.17.1
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