The following commit has been merged into the x86/irq branch of tip: Commit-ID: fe62bc23620fa027162e05594a610ff5e556496a Gitweb: https://git.kernel.org/tip/fe62bc23620fa027162e05594a610ff5e556496a Author: Maciej W. Rozycki <macro@xxxxxxxxxxx> AuthorDate: Thu, 31 Mar 2022 08:10:46 +01:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Sun, 10 Apr 2022 12:48:14 +02:00 x86/PCI: Add support for the SiS85C497 PIRQ router The SiS 85C496/497 486 Green PC VESA/ISA/PCI Chipset has support for PCI steering and the ELCR register implemented. These features are handled by the SiS85C497 AT Bus Controller & Megacell (ATM) ISA bridge, however the device is wired as a peer bridge directly to the host bus and has its PCI configuration registers decoded at addresses 0x80-0xff by the accompanying SiS85C496 PCI & CPU Memory Controller (PCM) host bridge[1]. Therefore we need to match on the host bridge's vendor and device ID. Like with the SiS85C503 PIRQ router handle link value ranges of 1-4 and 0xc0-0xc3, corresponding respectively to PIRQ line numbers counted from 1 and link register PCI configuration space addresses. References: [1] "486 Green PC VESA/ISA/PCI Chipset, SiS 85C496/497", Rev 3.0, Silicon Integrated Systems Corp., July 1995, Part IV, Section 3. "PCI Configuration Space Registers (00h ~ FFh)", p. 114 Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Tested-by: Nikolai Zhubr <zhubr.2@xxxxxxxxx> Link: https://lore.kernel.org/r/alpine.DEB.2.21.2203301610490.22465@xxxxxxxxxxxxxxxxx --- arch/x86/pci/irq.c | 80 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 80 insertions(+) diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c index e5bc9f7..4b0e008 100644 --- a/arch/x86/pci/irq.c +++ b/arch/x86/pci/irq.c @@ -580,6 +580,81 @@ static int pirq_cyrix_set(struct pci_dev *router, struct pci_dev *dev, int pirq, return 1; } + +/* + * PIRQ routing for the SiS85C497 AT Bus Controller & Megacell (ATM) + * ISA bridge used with the SiS 85C496/497 486 Green PC VESA/ISA/PCI + * Chipset. + * + * There are four PCI INTx#-to-IRQ Link registers provided in the + * SiS85C497 part of the peculiar combined 85C496/497 configuration + * space decoded by the SiS85C496 PCI & CPU Memory Controller (PCM) + * host bridge, at 0xc0/0xc1/0xc2/0xc3 respectively for the PCI INT + * A/B/C/D lines. Bit 7 enables the respective link if set and bits + * 3:0 select the 8259A IRQ line as follows: + * + * 0000 : Reserved + * 0001 : Reserved + * 0010 : Reserved + * 0011 : IRQ3 + * 0100 : IRQ4 + * 0101 : IRQ5 + * 0110 : IRQ6 + * 0111 : IRQ7 + * 1000 : Reserved + * 1001 : IRQ9 + * 1010 : IRQ10 + * 1011 : IRQ11 + * 1100 : IRQ12 + * 1101 : Reserved + * 1110 : IRQ14 + * 1111 : IRQ15 + * + * We avoid using a reserved value for disabled links, hence the + * choice of IRQ15 for that case. + * + * References: + * + * "486 Green PC VESA/ISA/PCI Chipset, SiS 85C496/497", Rev 3.0, + * Silicon Integrated Systems Corp., July 1995 + */ + +#define PCI_SIS497_INTA_TO_IRQ_LINK 0xc0u + +#define PIRQ_SIS497_IRQ_MASK 0x0fu +#define PIRQ_SIS497_IRQ_ENABLE 0x80u + +static int pirq_sis497_get(struct pci_dev *router, struct pci_dev *dev, + int pirq) +{ + int reg; + u8 x; + + reg = pirq; + if (reg >= 1 && reg <= 4) + reg += PCI_SIS497_INTA_TO_IRQ_LINK - 1; + + pci_read_config_byte(router, reg, &x); + return (x & PIRQ_SIS497_IRQ_ENABLE) ? (x & PIRQ_SIS497_IRQ_MASK) : 0; +} + +static int pirq_sis497_set(struct pci_dev *router, struct pci_dev *dev, + int pirq, int irq) +{ + int reg; + u8 x; + + reg = pirq; + if (reg >= 1 && reg <= 4) + reg += PCI_SIS497_INTA_TO_IRQ_LINK - 1; + + pci_read_config_byte(router, reg, &x); + x &= ~(PIRQ_SIS497_IRQ_MASK | PIRQ_SIS497_IRQ_ENABLE); + x |= irq ? (PIRQ_SIS497_IRQ_ENABLE | irq) : PIRQ_SIS497_IRQ_MASK; + pci_write_config_byte(router, reg, x); + return 1; +} + /* * PIRQ routing for SiS 85C503 router used in several SiS chipsets. * We have to deal with the following issues here: @@ -962,6 +1037,11 @@ static __init int serverworks_router_probe(struct irq_router *r, static __init int sis_router_probe(struct irq_router *r, struct pci_dev *router, u16 device) { switch (device) { + case PCI_DEVICE_ID_SI_496: + r->name = "SiS85C497"; + r->get = pirq_sis497_get; + r->set = pirq_sis497_set; + return 1; case PCI_DEVICE_ID_SI_503: r->name = "SiS85C503"; r->get = pirq_sis503_get;
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