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Code Issues Releases Wiki Activity

can: m_can: pci: use custom bit timings for Elkhart Lake

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The relevant datasheet [1] specifies nonstandard limits for the bit timing
parameters. While it is unclear what the exact effect of violating these
limits is, it seems like a good idea to adhere to the documentation.

[1] Intel Atom® x6000E Series, and Intel® Pentium® and Celeron® N and J
    Series Processors for IoT Applications Datasheet,
    Volume 2 (Book 3 of 3), July 2021, Revision 001

Fixes: cab7ffc032 ("can: m_can: add PCI glue driver for Intel Elkhart Lake")
Link: https://lore.kernel.org/all/9eba5d7c05a48ead4024ffa6e5926f191d8c6b38.1636967198.git.matthias.schiffer@ew.tq-group.com
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Matthias Schiffer 2021-11-15 10:18:52 +01:00 committed by Marc Kleine-Budde
parent ea22ba40de
commit ea4c178768
1 changed files with 44 additions and 4 deletions
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48
drivers/net/can/m_can/m_can_pci.c
View file

@ -18,9 +18,14 @@
#define M_CAN_PCI_MMIO_BAR 0
#define M_CAN_CLOCK_FREQ_EHL 200000000
#define CTL_CSR_INT_CTL_OFFSET 0x508
struct m_can_pci_config {
const struct can_bittiming_const *bit_timing;
const struct can_bittiming_const *data_timing;
unsigned int clock_freq;
};
struct m_can_pci_priv {
struct m_can_classdev cdev;
@ -84,9 +89,40 @@ static struct m_can_ops m_can_pci_ops = {
.read_fifo = iomap_read_fifo,
};
static const struct can_bittiming_const m_can_bittiming_const_ehl = {
.name = KBUILD_MODNAME,
.tseg1_min = 2, /* Time segment 1 = prop_seg + phase_seg1 */
.tseg1_max = 64,
.tseg2_min = 1, /* Time segment 2 = phase_seg2 */
.tseg2_max = 128,
.sjw_max = 128,
.brp_min = 1,
.brp_max = 512,
.brp_inc = 1,
};
static const struct can_bittiming_const m_can_data_bittiming_const_ehl = {
.name = KBUILD_MODNAME,
.tseg1_min = 2, /* Time segment 1 = prop_seg + phase_seg1 */
.tseg1_max = 16,
.tseg2_min = 1, /* Time segment 2 = phase_seg2 */
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 32,
.brp_inc = 1,
};
static const struct m_can_pci_config m_can_pci_ehl = {
.bit_timing = &m_can_bittiming_const_ehl,
.data_timing = &m_can_data_bittiming_const_ehl,
.clock_freq = 200000000,
};
static int m_can_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
{
struct device *dev = &pci->dev;
const struct m_can_pci_config *cfg;
struct m_can_classdev *mcan_class;
struct m_can_pci_priv *priv;
void __iomem *base;
@ -114,6 +150,8 @@ static int m_can_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
if (!mcan_class)
return -ENOMEM;
cfg = (const struct m_can_pci_config *)id->driver_data;
priv = cdev_to_priv(mcan_class);
priv->base = base;
@ -125,7 +163,9 @@ static int m_can_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
mcan_class->dev = &pci->dev;
mcan_class->net->irq = pci_irq_vector(pci, 0);
mcan_class->pm_clock_support = 1;
mcan_class->can.clock.freq = id->driver_data;
mcan_class->bit_timing = cfg->bit_timing;
mcan_class->data_timing = cfg->data_timing;
mcan_class->can.clock.freq = cfg->clock_freq;
mcan_class->ops = &m_can_pci_ops;
pci_set_drvdata(pci, mcan_class);
@ -178,8 +218,8 @@ static SIMPLE_DEV_PM_OPS(m_can_pci_pm_ops,
m_can_pci_suspend, m_can_pci_resume);
static const struct pci_device_id m_can_pci_id_table[] = {
{ PCI_VDEVICE(INTEL, 0x4bc1), M_CAN_CLOCK_FREQ_EHL, },
{ PCI_VDEVICE(INTEL, 0x4bc2), M_CAN_CLOCK_FREQ_EHL, },
{ PCI_VDEVICE(INTEL, 0x4bc1), (kernel_ulong_t)&m_can_pci_ehl, },
{ PCI_VDEVICE(INTEL, 0x4bc2), (kernel_ulong_t)&m_can_pci_ehl, },
{ } /* Terminating Entry */
};
MODULE_DEVICE_TABLE(pci, m_can_pci_id_table);